c Language

Example 1

Structure of C Program

Output

Keywords In C

Keyword in C are the reserved words in C which have some fixed job and cannot be used as identifier.

List of Keywords are:

Use of Control strings

Output

Use of Input Function (Scanf)

Output

Output String’s

#include<stdio.h>

void main()

{char ch=66;

char ch1=74,ch2=103,ch3='c',ch4[]="civil";

int f=5.67;

clrscr();

printf("%c,%d,%o,%x,%ld,%ld,%d,\n",ch,72,72,72,32770,32887,32769);

printf("%f,\n",3.24);

printf("%d,\n",f);

printf("%c,\n%c,\n",ch1,ch2);

printf("%d,\n",'\n');

printf("%d,\n",'A');

printf("%c,\n",'B');

printf("%c,\n",ch3);

printf("%s",ch4);

getch();}

//Operators and their precedence.#include<stdio.h>void main(){char ch;int x,z,b=3;float a=1.5;long int j;double d;long double e;clrscr();printf("%d\n",sizeof(ch));printf("%d\n",sizeof(x));printf("%d\n",sizeof(a));printf("%d\n",sizeof(j));printf("%d\n",sizeof(d));printf("%d\n",sizeof(e));printf("%ld\n",&x);printf("%d\n",b/2);printf("%f",a/2);x=3+4-7*8/5%10;printf("%d\n",x);printf("%d\n",+x);printf("%d\n",-x);z=++x + ++x + ++x;printf("%d\n",z);printf("%d\n",++z);printf("%d\n",z++);printf("%d\n",z);a=b/2+b*8/b-b+a/3;printf("%f",a);getch();}

Output

Example1:(Operators)

#include<stdio.h>void main(){int x,y,z;x=1;y=2;z=4;clrscr();z=x+y*z/4%2-1;printf("%d%d%d",x,y,z);getch();}

Output of Example1:

Example 2;(operators)

#include<stdio.h>

void main()

{

int a=10,b=10;

clrscr();

printf("ans=%d",a>b?a*a:b/b);

getch();

}

Example 3(Operators):

#include<stdio.h>void main(){int c=0,d=5,e=10,a;clrscr();a=(c>1?(d>1|| e>1? 100:200):300);printf("a=%d",a);getch();}

Output (Example 3):

Example4(operators)

#include<stdio.h>void main(){int x=3,y=4,z=4;clrscr();printf("ans=%d",(z>=y>=x?100:200));getch();}

Output(Example4):

Example 5:#include<stdio.h>void main(){int x=5;printf("x=%d\n",x++);printf("%d\n",x);printf("x=%d\n",++x);printf("%d\n",x);getch();}

Output Example5:

Operators(Ex:1)

#include<stdio.h>void main(){int x=3,y,z;clrscr();z=y=x;z*=y=x*x;printf("x=%d,y=%d,z=%d",x,y,z);getch();}

Output

Operators(Ex:2)

#include<stdio.h>

void main()

{

int a=30,b=40,x;

clrscr();

x=(a!=10) && (b=50);

printf("x=%d",x);

getch();

}

Output

Operators(Ex3)

#include<stdio.h>void main(){int x=10,y=x,z=x,t;clrscr();y-=x;z=-x;t=-x;printf("y=%d,z=%d,t=%d",y,z,t);getch();}

Output

Operators

#include<stdio.h>void main(){int x,y,z;clrscr();x=y=z=1;z=++x || ++y && ++z;printf("x=%d,y=%d,z=%d",x,y,z);getch();}

Output

Control Statements

• Decision Control Statements -The If Statement

-The If - Else Statement

-The switch Statement

• Looping Control Statements

• Breaking Control Statements

• Jump Statements

The If Statement

Syntax:

If(condition)

{

statement 1;

statement 2;

}

The if-else statement

Syntax:if(condition) // no semicolon{statement 1;statement 2; }else{statement 3;statement 4;}

Example 1:

#include<stdio.h>void main(){int m,n;clrscr();scanf("%d%d",&m,&n);if (m-n==0)printf("two numbers are equal");elseprintf("xyz");getch();}

Output

Example 2:

#include<stdio.h>void main(){int a=300,b=10,c=20;clrscr();if (!(a>=400)){b=300;c=200;printf("b=%d c=%d",b,c);}elseprintf("civil");getch();}

Output:

Example 3:#include<stdio.h>void main(){int a=10,b=100%90;clrscr();if (a!=b)printf("a=%d b=%d",a,b);elseprintf("thapar");getch();}

Output

Nested if statementsSyntax:if(condition 1){ if(condition 2) statement 1; else statement 2;}else statement 3;

Example 1:

#include<stdio.h>void main(){int a,b;clrscr();scanf("%d%d",&a,&b);if(a<=b){if(a<b)printf("%d < %d",a,b);elseprintf("%d == %d",a,b);}elseprintf("%d > %d",a,b);getch();}

Output:

Dangling Else Problem

if(condition 1)

if(condition 2)

statement 1;

else

statement 2;

// This problem is created when there is no matching else for every if. In C to overcome this problem else is always paired with most recent unpaired if.

Multiway selection:switch statement Syntax:switch(variable or expression){case constant A:Statement 1;break;case constant B:Statement 2;break;……default:Statement;}

Example 1:#include<stdio.h>void main(){int a;clrscr();scanf("%d",&a);switch (a){case 1:printf("........");break;case 2:printf("********");break;default:printf("invalid option");}getch();}

Output

Example 2:#include<stdio.h>void main(){int k=-2,j=4;clrscr();switch (k/=j/k){default:printf("all are same\n");case 0:printf("abc\n");case 1:printf("xyz\n");case 2:printf("civil");}getch();}

Output

Looping Control Statements(Used for Iterations)

• for loop.

Nested for loops(for with in for)

• while loop (Entry Controlled Loop).

• do-while loop (Exit Controlled Loop).

Example 1:#include<stdio.h>void main(){int i;clrscr();for(i=0;i<3;i++){printf("%d\n",i);}getch();}

Output 1:

Example 2:#include<stdio.h>void main(){int i;clrscr();for(i=0;i<=4;i++){printf("%d\n",i);}getch();}

Output 2:

Example 3:#include<stdio.h>void main(){int i;clrscr();for(i=0;i<=3;i++){printf("civil\n");printf("%d\n",i);}getch();}

Output 3:

Example 4:#include<stdio.h>void main(){int j,x=0;clrscr();for(j=0;j<=5;j++){switch(j-1){case 0:case -1:x+=1;break;case 1:case 2: case 3:x+=2;break;default:x+=3;}printf("%d\n",x);}getch();}

Output:

Example 1:(Nested for)

#include<stdio.h>void main(){int i,j;clrscr();for(i=1;i<=3;i++){for(j=1;j<=2;j++){printf("i=%d,j=%d\n",i,j);printf("i*j=%d\n",i*j);}}getch();}

Output:

Example 2:#include<stdio.h>void main(){int a,b,sub;clrscr();for(a=3;a>=1;a--){for(b=1;b<=2;b++){sub=a-b;printf("a=%d,b=%d,sub=%d\n",a,b,sub);}}getch();}

Output:

Example 3:(with middle loop)#include<stdio.h>

void main(){int a,b,c;

clrscr();

for(a=1;a<=2;a++)

{

for(b=1;b<=2;b++)

{

for(c=1;c<=2;c++){

printf("a=%d,b=%d,c=%d,a+b+c=%d\n",a,b,c,a+b+c);

}}}

getch();}

Output:

Example 4:

#include<stdio.h>void main(){int a;clrscr();for(a=1;a<=32767;a++){printf("%d",a);}getch();}

Example 5:#include<stdio.h>void main(){int x=1;clrscr();switch(x){printf("hello\n");case 1:printf("xyz\n");break;default:printf("abc\n");}getch();}

Output:

Break Statement:Used to take the control out of the body of current loop.

#include<stdio.h>

void main(){

int i;clrscr();

for(i=1;i<=5;i++){

if(i==3)

break;

else

printf("%d",i);}

printf("\nxyz");

getch();}

Output:

Continue Statement:Doesn’t take the control out of the body of current loop but skips the statements following continue statement and takes the control

back to the next iteration of loop. #include<stdio.h> /*Program for continue*/void main(){int i;clrscr();for(i=1;i<=10;i++){if(i==4)continue;elseprintf("%d\n",i);}printf("\nabd");getch();}

Output:

Use of both break and continue#include<stdio.h>void main(){int i;clrscr();for(i=-1;i<=10;i++){if(i<=5)continue;elsebreak;printf("civil");}printf("\nxyz");getch();}

Output:

The while LOOP

Syntax:

while(test condition)

{

body of while loop

}

The test condition may be any expression.The loop statements will be executed till the condition is true.

Example 1:

#include<stdio.h>void main(){int i=1;clrscr();while(i<=5){printf("%d",i);i++;}printf("\nabc");getch();}

Output:

Example2:#include<stdio.h>void main(){int c=1,d=0;clrscr();while(d<=9){printf("\n%d %d",++d,++c);}printf(“xyz”);getch();}

Output:

Example 3:#include<stdio.h>void main(){int i=5;clrscr();while(i-->=0)printf("%d",i);i=5;printf("\n");while(i-->=0)printf("%d",i);printf("\n");while(i-->=0)printf("%d",i);getch();}

Output:

The do-while LOOP(Exit Controlled Loop)

Syntax:

do

{

Body of loop

}while(test condition);

Regardless of the test condition body of loop will executed at least once.

true

Example 3#include<stdio.h>void main(){int i=5;clrscr();do{printf("%d",i);i--;}while(i>=0);getch();}

Output:

Example 4:#include<stdio.h>void main(){int i=5;clrscr();do{printf("%d",i);i--;}while(i<=0);getch();}

Output:

goto statement

Syntax:

goto label;-----label: This statement does not contain any

condition.This statement passes control anywhere in the program where the label is used.

label name must start with any character.

goto statement example:#include<stdio.h>void main(){int a;clrscr();printf("Enter a number");scanf("%d",&a);if(a%2==0)goto even;elsegoto odd;even:printf("%d is a even number",a);exit(0);odd:printf("%d is a odd number",a);getch();}

Output goto:

goto statement#include<stdio.h>void main(){int i,j;clrscr();for(j=1;j<=10;j++){for(i=1;i<=10;i++){if(j<10)goto xyz;}printf("civil\n");printf("abc\n");}xyz:printf("the null chracter discards \0 the rest of line\n");printf("\nthis is \"cse\" in double quotes\n");printf("this is \\ escape character itself\n");printf("this line disappears.\r...reposition at the beginning\

n");getch();}

Output:

Problems:Control Structures1.Write a program to find factorial of a

number using do-while.

2.Write a program to display numbers from 1 to 16.Use incrementation operation in body of for loop more than once.

3.Write a program to print the entered number in reverse order using do-while loop.Also perform sum and multiplication with their digits.

ArraysConsider the following example: #include<stdio.h>

void main(){

int a=2;

a=4;clrscr();

printf("%d",a);

getch();} OUTPUT:4

i.e ordinary variables are always capable of storing one value at a time(recent value).

Array variables are able to store more than one value at a time.

Declaration of an arrayDeclaration of an array is done as follows: Array is used to hold the values of similar data

type.i.e integer type of array holds only integer type of values,float type of array is used to hold floating type of values.

int a[5]; It tells the compiler that ‘a’ is an integer type of array and can store 5 integers.

In the same way different data types can be represented as array:For Ex:

char ch[10];//nothing but creation of 10 variables of //char type in the memory.Instead of

declaring 10 variables for 10 values,the //programmer can define them in an array.

float x[4];long num[7];

Array Initialization#include<stdio.h>void main(){int i[5]={1,2,5,6,7}; //Array Intialization clrscr();printf("1st element of array=%d\n",i[0]);printf("2nd element of array=%d\n",i[1]);printf("3rd element of array=%d\n",i[2]);printf("4th element of array=%d\n",i[3]);printf("5th element of array=%d\n",i[4]);getch();}

Output:

Example 1:#include<stdio.h>void main(){int i[5]={1,2};clrscr();printf("%d\n",i[0]);printf("%d\n",i[1]);printf("%d\n",i[2]);printf("%d\n",i[3]);printf("%d\n",i[4]);getch();}

Output:

Example 2:#include<stdio.h>void main(){float i[4]={12.4,2.5};float a[]={12.4,2.5,3.3}; ///clrscr();printf("%d\n",sizeof(i));printf("%d\n",sizeof(a));getch();} ///if the array is initialized where it is declared

mentioning the dimension of array is optional,as in above example.

Output:

Example 3:#include<stdio.h>

void main(){

float i[]={12.4,2.5,4.5,5.5};

clrscr();

printf("%d\n",sizeof(i)/sizeof(i[0]));

printf("%f\n",i[1]);

printf("%f\n",i[3]);

getch();

}

Output:

Example (Starting address=65516)

#include<stdio.h>

void main(){

int a[5]={5,20,36,47,60};

clrscr();

printf("%u\n%u\n%u\n%d\n%u\n%u\n%d",a,&a,&a[0],a[0],&a[1],&a[4],a[4]);

getch();

}

Output:

Inputting values from keyboard in array

#include<stdio.h>void main(){int arr[5],i;clrscr();for(i=0;i<5;i++){scanf("%d",&arr[i]);printf("the element is=%d",arr[i]);}getch();}

Output

Swap the elements of an array#include<stdio.h>void main(){int arr[2]={10,20},temp;clrscr();printf("%d,%d",arr[0],arr[1]);temp=arr[0];arr[0]=arr[1];arr[1]=temp;printf("\n%d,%d",arr[0],arr[1]);getch();}

Output

Example 4:#include<stdio.h>void main(){int a[5]={5,10,15,20,25},i,j,m,k;clrscr();i=++a[1];j=a[1]++;printf("i=%d\nj=%d\na[1]=%d\n",i,j,a[1]);i=1;m=a[i++];printf("i=%d\nm=%d\n",i,m);i=2;k=a[++i];printf("i=%d\nk=%d\n",i,k);getch();}

Output

Static array#include<stdio.h>void main(){int arr[6];static int b[4];int i;clrscr();for(i=0;i<6;i++){printf("%d\n",arr[i]);}printf("\n");for(i=0;i<4;i++){printf("%d\n",b[i]);}getch();}

Output

Example 5:(Assign Values)

#include<stdio.h>void main(){int a[5],i;for(i=0;i<5;i++){a[i]=i*2;printf("%d\n",a[i]);}getch();}

Output

2-D Arrays#include<stdio.h>void main(){int a[3][3]={2,4,3, 6,8,5, 3,5,1},i,j;clrscr();for(i=0;i<3;i++){for(j=0;j<3;j++)printf("%d",a[i][j]); to print in matrix form line

is left as in next caseprintf(“\n”);}getch();}

Output

2-D Arrays(Continued)#include<stdio.h>void main(){int a[3][3]={2,4,3, 6,8,5, 3,5,1};clrscr();printf("%u\n%u\n%u",a,a[2],a[2][2]);getch();}

Output

FunctionsA function is self contained block of code that

performs task of some kind.

Ex: Sum(int x,int y) is used to find sum of two integers.

Example 1:#include<stdio.h>void main(){int x,y,z;x=3;y=4;z=sum(x,y); //Calling Functionprintf("%d",z);getch();}int sum(int a,int b) //Function definition(Called Fn){int c;c=a+b;return c;}

Output

Some facts about Functions:1.Functions can be either library functions or

user defined.

2.There can be any number of the functions in the program.

3.Program execution always begin with main().

4.Communication b/w the functions is called a message passing.

Example 2:#include<stdio.h>float areacircle(float); //Function Prototypevoid main(){int area;float radius=2.0;clrscr();area=areacircle(radius);printf("%d",area);getch();}float areacircle(float r){float a;a=3.14*r*r;printf("%f\n",a);return a;}

Output

Message Passing

• Call By value

• Call By address

In Call by value we pass the value from calling to called function.

In Call By address we pass the address from calling to called function.

In Call by address we make use of Pointers.

PointersPointer is used to hold the address of any

other variable.The pointer is denoted by (*)asterisk symbol.

It has two parts one is called as declaration part and other is reference part.

For Ex: int *x,i; //declaration part

This statement tells the compiler that it holds the address of any integer variable.

Similarly float *y;

x=&i; //reference part

Pointers(* gives value at address)#include<stdio.h>void main(){int i=30;int *j,**k; //declaration partclrscr();j=&i; //dereferencing partk=&j;printf("%u\n",&i);printf("%u\n",j);printf("%u\n",*&i); // i=30 j=65524 k=65522 printf("%d\n",*j); //&i=65524 &j=65522 printf("%u\n",k);printf("%u\n",*k);printf("%d",**k);getch();}

Output

Pointers continued…#include<stdio.h>void main(){int i=30;int ***r,**q,*p;clrscr();p=&i;q=&p;r=&q;printf("%d\n",*p);printf("%d\n",**q);printf("%d",***r);getch();}

Output

Functions continued….#include<stdio.h>void main(){int i=3,k,l;clrscr();k=add(++i);l=add(i++);printf("%d\n%d\n%d",i,k,l);getch();}int add(int x){++x;return x;}

Output

Functions Ex2:#include<stdio.h>void main(){int k=35,z;clrscr();k=func1(k=func1(k=func1(k)));printf("k=%d",k);getch();}int func1(int x){++x;return x;}

Output

Types of functions1.(without arguments and without return values)

#include<stdio.h>void message();void main(){clrscr();message();getch();}void message(){printf("civil");}

Output

2.With arguments but without return values

#include<stdio.h>void sqr();void main(){int j;clrscr();for(j=1;j<5;j++)sqr(j);getch();}void sqr(int k){printf("%d\n",k*k);}

Output

3.With arguments and return values#include<stdio.h>int sqr();void main(){int j,i;clrscr();for(j=1;j<4;j++){i=sqr(j);printf("square=%d\n",i);}getch();}sqr(int k){return (k*k);}

Output

4.Without Arguments but with return values

#include<stdio.h>int sum();void main(){int j,i;clrscr();i=sum();printf("sum=%d",i);getch();}sum(){int x,y,z;scanf("%d%d%d",&x,&y,&z);return (x+y+z);}

Output

Use of Operator with function#include<stdio.h>#include<math.h>int y(),sqr(int),cube(int);void main(){int x,i;clrscr();scanf("%d",&x);i=x>y()? sqr(x):cube(x);printf("%d",i);getch();}y(){return (10);}sqr(int k){return (pow(k,2));}cube(int k){return (pow(k,3));}

Output

Example:2#include<stdio.h>int addsub(int,int);void main(){int i=10,j=20,k;clrscr();k=addsub(i,j);printf("%d",k);getch();}addsub(int c,int d){int x,y;x=c-d;y=c+d;return(x);return(y);}

Output

Example 3:#include<stdio.h>int addsub(int,int);void main(){int i=10,j=20,k;clrscr();k=addsub(i,j);printf("%d",k);getch();}addsub(int c,int d){int x,y;x=c-d;y=c+d;return(x,y);}

Output

Call by value

#include<stdio.h>void main(){

int a=10,b=20;clrscr();

swap(a,b);

printf("%d%d",a,b);

getch();}

int swap(int x,int y)

{int t;

t=x;

x=y;

y=t;

printf("%d%d\n",x,y);}

Output

Call By Reference#include<stdio.h>void main(){int a=10,b=20;clrscr();swap(&a,&b);printf("%d%d",a,b);getch();}int swap(int *x,int *y){int t;t=*x; //t=a;*x=*y; //a=b*y=t; //b=tprintf("%d%d\n",*x,*y);}

Output

Functions with Arithmetic Eqns#include<stdio.h>#include<math.h>int a(),b(),sqr(int);void main(){int s=0,k;clrscr();s=sqr(a()+b());printf("\n Square of sum=%d",s);getch();}a(){int a;printf("Enter the value of a");scanf("%d",&a);return a;}b(){int b;printf("Enter the value of b");scanf("%d",&b);return b;}sqr(int x){return (pow(x,2));}

Output

Call to Function through if #include<stdio.h>int a();void main(){clrscr();if(a()%2==0)printf("\n Even Number");elseprintf("\n Odd Number");getch();}a(){int a;printf("Enter the value of a");scanf("%d",&a);return a;}

Output

Example#include<stdio.h>int addmul(int,int);void main(){int i=3,j=4,k,l;clrscr();k=addmul(i,j);l=addmul(i,j);printf("%d,%d",k,l);getch();}int addmul(int a,int b){int x,y;x=a + b;y=a * b;return(x,y);}

Output

Address of the Function.#include<stdio.h>void show();void main(){clrscr();show();printf("%u",show);getch();}void show(){printf("\naddress of the function show() is :");}

Output

Example#include<stdio.h>void fun(int *,int *);void main(){int i=5,j=2;clrscr();fun(&i,&j);printf("%d,%d",i,j);getch();}void fun(int *a,int *b){*a=*a * *a;*b=*b * *b;}

Output

Recursive Functions#include<stdio.h>int fact(int);void main(){int k=5,l;clrscr();l=fact(k);printf("%d",l); //stack is used.(LIFO)getch();} //data structure.is the particularint fact(int n) //way of storing data in computer.//{int f;if (n==0)return 1;elsef=n*fact(n-1);return f;}

Output

Example(Diff B/w call by value and Reference)

#include<stdio.h>int xyz(int,int*);void main(){int i=-5,j=-2;clrscr();xyz(i,&j);printf("%d,%d",i,j);getch();}int xyz(int x,int *y){x=x * x;*y=*y * *y;}

Output

Arrays and Functions#include<stdio.h>int d(int);void main(){int i,k;int m[5]={55,65,75,85,95};clrscr();for(i=0;i<5;i++){k=d(m[i]);printf("%d,",k);}getch();}int d(int n){return n;}

Output

Arrays and Functions(reference) #include<stdio.h>int s(int*);void main(){int i,k;int m[5]={55,65,75,85,95};clrscr();for(i=0;i<5;i++){k=s(&m[i]);printf("%d,",k);}getch();}int s(int *n){return *n;}

Output

Pointers and Arrays#include<stdio.h>void main(){int i,*j;int m[5]={55,65,75,85,95};clrscr();j=&m[0];for(i=0;i<5;i++){printf("%u\t",&m[i]);printf("%d\n",*j);j++;} /*pointer when incremented points to

immediate next location of array element*/getch();}

Output

Strings

#include<stdio.h>void main(){char name1[7]={'s','a','n','j','a','y'};char name2[6]={"civil"};char name3[6]={"civ\0il"};clrscr();printf("%s\n",name1);printf("%s\n",name2);printf("%s",name3);getch();}

Output

Strings with different formats

#include<stdio.h>void main(){char text[15]={"Computers"};clrscr();printf("%s\n",text);printf("%.5s\n",text);printf("%.8s\n",text);printf("%11s\n",text);getch();}

Output

While loop to print array of Characters

#include<stdio.h>

void main(){

char text[]={"CIVIL ENGG"};

int i=0;

clrscr();

while(i<=10)

{printf("%c",text[i]);

i++;}

getch();

}

Output

While by taking help of ‘\0’character

#include<stdio.h>void main(){char text[]={"CIVIL ENGG"};int i=0;clrscr();while(text[i]!=‘\0’){printf("%c",text[i]);i++;}getch();}

Output

String I/P, O/P#include<stdio.h>void main(){char month[9];char str[10];clrscr();printf("enter the month\n");scanf("%s",&month);scanf("%s",&str);printf("%s\n",month);printf("%s",str);getch();}

Output

gets,puts and length of string

#include<stdio.h>#include<string.h>void main(){char text[20];int len;clrscr();printf("type text below.\n");gets(text);len=strlen(text);printf("length of string=%d\n",len);puts(text);getch();}

Output

strcpy(s2,s1) s1 is copied to s2.#include<stdio.h>#include<string.h>void main(){char s1[9];char s2[10];clrscr();printf("enter string s1\n");gets(s1);printf("enter string s2\n");gets(s2);strcpy(s2,s1);puts(s2);getch();}

Output

strncpy(s2,s1,n)copies specified length of characters

#include<stdio.h>#include<string.h>void main(){char s1[9];char s2[10];int n;clrscr();printf("enter string s1\n");gets(s1);printf("enter string s2\n");gets(s2);scanf("%d",&n);strncpy(s2,s1,n);puts(s2);getch();}

Output

strcmp(s1,s2)#include<stdio.h>#include<string.h>void main(){char s1[9];char s2[10];int diff;clrscr();printf("enter string s1\n");gets(s1);printf("enter string s2\n");gets(s2);diff=strcmp(s1,s2);if(diff==0)printf("s1 and s2 are identical");elseprintf("s1 and s2 are not identical");getch();}

Output

strncmp(s1,s2,n)compares upto first n characters

#include<stdio.h>#include<string.h>void main(){char s1[9];char s2[10];int diff,n;clrscr();printf("enter string s1\n");gets(s1);printf("enter string s2\n");gets(s2);scanf("%d",&n);diff=strncmp(s1,s2,n);if(diff==0)printf("s1 and s2 are identical");elseprintf("s1 and s2 are not identical");getch();}

Output

strlwr(upper)convert to lower case

#include<stdio.h>#include<string.h>void main(){char s1[9];clrscr();printf("enter string s1\n");gets(s1);printf("%s",strlwr(s1));getch();}

Output

strupr#include<stdio.h>#include<string.h>void main(){char s1[9];clrscr();printf("enter string s1\n");gets(s1);printf("%s",strupr(s1));getch();}

Output

Strcat(to concatenate s1 and s2) #include<stdio.h>#include<string.h>void main(){char s1[20];char s2[10];clrscr();printf("enter string s1\n");gets(s1);printf("enter string s2\n");gets(s2);strcat(s1,s2);puts(s1);getch();}

Output

Strncat(to append n chars of s2 in s1 )

#include<stdio.h>#include<string.h>void main(){char s1[20];char s2[10];int n;clrscr();printf("enter string s1\n");gets(s1);printf("enter string s2\n");gets(s2);scanf("%d",&n);strncat(s1,s2,n);puts(s1);getch();}

Output

Strrev(s1)reverse the string

#include<stdio.h>#include<string.h>void main(){char s1[20];clrscr();printf("enter string s1\n");gets(s1);strrev(s1);puts(s1);getch();}

Output

Strset(s1,symbol)#include<stdio.h>#include<string.h>void main(){char s1[20];char c;clrscr();printf("enter string s1\n");gets(s1);printf("enter symbol");scanf("\n%c",&c);strset(s1,c);puts(s1);getch();}

Output

Strnset(s1,symbol,n)#include<stdio.h>#include<string.h>void main(){char s1[20],c;int n;clrscr();printf("enter string s1\n");gets(s1);printf("enter symbol");scanf("\n%c",&c);scanf("%d",&n);strnset(s1,c,n);puts(s1);getch();}

Output

Strspn(return the position where source array does not match with destination

#include<stdio.h>#include<string.h>void main(){char s1[20];char s2[10];int n;clrscr();printf("enter string s1\n");gets(s1);printf("enter string s2\n");gets(s2);n=strspn(s1,s2);printf("%d",n);getch();}

Output

Copy string w/o using strcpy();#include<stdio.h>#include<string.h>void main(){char ori[20], dup[20];int i;clrscr();printf("enter string ori\n");gets(ori);for(i=0;ori[i]!='\0';i++)dup[i]=ori[i];dup[i]='\0';puts(dup);getch();}

Output

String is palindrome or not#include<stdio.h>#include<string.h>void main(){char str[10];int i=0,j,k;clrscr();printf("enter string str\n");gets(str);j=strlen(str)-1;for(i=0;i<=j;i++){if(str[i]==str[j])k=1;else {k=0;break;}j--;}if (k==1)printf("word is palindrome");else printf("word is not palindrome");getch();}

Output

String elements can also be accessed using Pointers

#include <stdio.h>void main (){char *ptr="civil";clrscr();while(*ptr!='\0'){printf("%c",*ptr);ptr++;}getch();}

Output

Structures(used to hold dissimilar data type under single name)

#include<stdio.h>void main(){struct book1{char book[30];int pages;float price;};struct book1 bk1={"cprograms",345,123};clrscr();printf("%s\n",bk1.book);printf("%d\n",bk1.pages);printf("%f",bk1.price);getch();}

Output

Size of structure type variable#include<stdio.h>void main(){struct book1{char book[30];int pages;float price;};struct book1 bk1={"cprograms",345,123};clrscr();printf("%d bytes\n",sizeof(bk1.book));printf("%d bytes\n",sizeof(bk1.pages));printf("%d bytes\n",sizeof(bk1.price));printf("%d bytes\n",sizeof(bk1));getch();}

Output

More about structures#include<stdio.h>void main(){struct player{char name[30];int age;}p1={"xyz",23};clrscr();printf("%s\n",p1.name);printf("%d\n",p1.age);getch();}

Output

Assignment of one structure variable into another

#include<stdio.h>void main(){struct player{char name[30];int age;}p1={"xyz",23};struct player p2;clrscr();p2=p1;printf("%s\n",p2.name);printf("%d\n",p2.age);getch();}

Output

Array of Structures#include<stdio.h>void main(){struct employee{int eno;char name[20];};struct employee a[3];int i;clrscr();for(i=0;i<3;i++){printf("Enter empno and name of employee");scanf("%d%s",&a[i].eno,&a[i].name);}for(i=0;i<3;i++)printf("Empno=%d,name=%s\n",a[i].eno,a[i].name);getch();}

Output

Pointer to structure#include<stdio.h>void main(){struct book{char name[20];char author[25];int pages;};struct book b1={"Cprograms","kanetkar",589};struct book *ptr;clrscr();ptr=&b1;printf("%s %s %d\n",b1.name,b1.author,b1.pages);printf("%s %s %d",ptr->name,ptr->author,ptr->pages);getch();}

Output

Structure and function(passing entire structure)#include<stdio.h>struct xyz{char name[20];int age;};void main(){struct xyz b1={"abc",23};clrscr();show(b1);getch();}show(struct xyz b2){printf("%s %d",b2.name,b2.age);return 0;}

Output

Structure and functions(passing reference)#include<stdio.h>struct book{char name[20];char author[25];int pages;};void main(){struct book b1={"Cprograms","kanetkar",589};clrscr();show(&b1);getch();}show(struct book *b2){printf("%s %s %d",b2->name,b2->author,b2->pages);return 0;}

Output

Passing structure elements to functions#include<stdio.h>struct xyz{char name[20];int age;};void main(){struct xyz b1={"abc",23};clrscr();show(&b1.name,b1.age);getch();}show(char *s,int z){printf("%s %d",s,z);return 0;}

Output

Structure within structure#include<stdio.h>void main(){struct part{char type[20];int qty;};struct vehicle{char xyz[20];struct part p1;};struct vehicle v1;v1.p1.qty=300;printf(“qty=%d",v1.p1.qty);getch();}

Output

Memory Organization of structure elements#include<stdio.h>#include<string.h>void main(){struct xyz{int num;float f;char branch[10];}a;clrscr();a.num=1; //assume starting address =65510a.f=3.14;strcpy(a.branch,"civil");printf("%u %u %u\n",&a.num,&a.f,&a.branch);printf("%d %f %s",a.num,a.f,a.branch);getch();}

Output

Memory w.r.t array of structures /*starting address of 1st struct is=65514*/#include<stdio.h>void main(){struct a{int num;float f;}v[2];clrscr();printf("%u %u\n",&v[0].num,&v[0].f);printf("%u %u",&v[1].num,&v[1].f);getch();}

Output

[Union(same portion of memory is accessed by member elements]

#include<stdio.h>void main(){struct a{int num;float f; }v;union b{float f;int num;}s;clrscr();printf("%d bytes\n",sizeof(v));printf("%d bytes",sizeof(s));getch();}

Output

Access elements of union

#include<stdio.h>void main(){union b{float f;int num;}s;clrscr();scanf("%f %d",&s.f,&s.num);printf("%f %d",s.f,s.num);getch();}

Output

Pointers and arrays#include<stdio.h>void main(){int num[4]={10,25,45,60},i;clrscr();printf("address element \n");for(i=0;i<4;i++){printf("%u\t",num+i);printf("num[%d]=%d\n",i,*(num+i));}getch();}

Output

Arrays and pointers#include<stdio.h>void main(){int arr[5]={10,20,30,40,50},p;clrscr();for(p=0;p<5;p++){printf("value of arr[%d]=",p);printf("%d |",arr[p]);printf("%d |",*(arr+p));printf("%d |",*(p+arr));printf("%d |",p[arr]);printf("address of arr[%d]=%u\n",p,(arr+p));}getch();}

Output

2-d array#include<stdio.h>void main(){int mat[3][3],i,j;clrscr();for(i=0;i<3;i++){for(j=0;j<3;j++)scanf("%d",&mat[i][j]);}for(i=0;i<3;i++){for(j=0;j<3;j++)printf("%d",mat[j][i]);printf("\n");}getch();}

Output

Storage classes1. It tells the compiler about scope of the variable.

2. The initial value of the variable if already not initialized.

3. Life of the variable i.e how long the variable would be active in the program.

4. Storage area of variables.

C can have four storage classes

1.Automatic variables.

2.External variables.

3.static variables.

4.Register variables.

Automatic variables#include<stdio.h>void main(){int x=10;clrscr();printf("x=%d",x);{int x=20;printf("\nx=%d",x);}printf("\nx=%d",x);getch();}

Output

External Variables#include<stdio.h>int x=10;void main(){int x;clrscr();printf("x=%d",x);getch();}

Output

Continued..

#include<stdio.h>int x=10;void main(){extern int x;clrscr();printf("x=%d",x);getch();}

Output

Static Variables

#include<stdio.h>void main(){int x=10;static int y;clrscr();printf("x=%d y=%d",x,y);getch();}

Output

Register Variables

#include<stdio.h>

void main()

{

register int y=10;

clrscr();

printf("y=%d",y);

getch();

}

output

Size of pointer variables#include<stdio.h>void main(){int *p;char *c;float *f;clrscr();printf("%d\n",sizeof(p));printf("%d\n",sizeof(c));printf("%d\n",sizeof(f));printf("%u\n",&p);printf("%u\n",&c);printf("%u\n",&f);getch();}

Output