C Programming - Strings

8/8/2019 C Programming - Strings

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C PROGRAMMING - STRINGS


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Strings

A string is an array of characters.

Strings must have a 0 or null character afterthe last character to show where the string

ends. The null character is not included in thestring.

Two ways of using strings are: The first is with a character array and

the second is with a string pointer. A character array is declared in the same

way as a normal array. Example: char ca[10];


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Strings

Any sequence or set of characters defined

within double quotation symbols is a

constant string. Set the value of each individual element of

the array to the character you want and

you must make the last character a 0.

Remember to use %swhen printing the

string.


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Strings

In C, it is required to do some meaningful

operations on strings:

Reading string displaying strings Combining or concatenating strings

Copying one string to another.

Comparing string & checking whether they are

equal

Extraction of a portion of a string


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Reading Strings from the terminal

The function scanf with %s format

specification is needed to read the character

string from the terminal. Example:char address[15];

scanf(%s,address);

scanf statement has a draw back it just

terminates the statement as soon as it finds a

blank space


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Reading Strings from the terminal

The function getchar can be used repeatedlyto read a sequence of successive singlecharacters and store it in the array.

We cannot manipulate strings since C does notprovide any operators for string. For instance wecannot assign one string to another directly. For example:String=xyz;

String1=string2;

The example about is not valid. To copy thechars in one string to another string we may doso on a character to character basis.


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char ca[10];ca[0] = 'H';ca[1] = 'e';

ca[2] = 'l';ca[3] = 'l';ca[4] = 'o';ca[5] = 0;

printf("%s",ca); String pointers are declared as a pointer to a

char. char *sp;


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String handling functions

The string.h header file has some

useful functions for working with strings.

strcpy(destination,source) strcpy copies the source string to the

destination string.

s1 = "abc";

s2= "xyz";

strcpy(s1,s2); // s1 = "xyz"


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strcat(destination,source)

Joins the destination and source strings and

puts the joined string into the destinationstring.

s1 = "abc";

s2= "xyz";

strcat(s1,s2); // s1 = "abcxyz"


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strcmp(first,second)

Compares the first and second strings. If the

first string is greater than the second one thena number higher than 0 is returned. If the first

string is less than the second then a number

lower than 0 is returned. If the strings are

equal then 0 is returned.

s1 = "abc";

s2= "abc";

i =strcmp(s1,s2); // i = 0


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strcmp(first,second)

strcmp(Newyork,Newyork)

will return zero because the two strings are equal. strcmp(their,there)

will return a 9 which is the numeric difference

between ASCII i and ASCII r.

strcmp(The, the)

will return 32 which is the numeric difference

between ASCII T & ASCII t.


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strcmpi() function

This function is same as strcmp() which compares

two strings but not case sensitive.

Examplestrcmpi(THE,the);

will return 0.


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strlen(string)

Returns the amount of characters in a string.

s= "abcde";i =strlen(s); // i = 5


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strlen(string)

Returns the amount of characters in a string.

s= "abcde";i =strlen(s); // i = 5


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/* Everyones first C program. */

#include

char hello[13] = { 'H', 'e',

'l', 'l', 'o', ' ,'W', 'o',

'r', 'l', 'd', '!', '\0' };

main() {clrscr();

printf("%s\n", hello);

getch;}


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C Programming - Strings