Declarations, Assignments & Expressions in C

By:

Mr. Baha Hanene

Chapter 4

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LEARNING OUTCOMESThis chapter will cover learning outcome no.

2 i.e.

Use basic data-types and input / output in C programs. (L02)

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CONTENTSDeclarationsData typesAssignment StatementsExpression StatementsFormat Specifiers

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DECLARATIONSThe declaration means list all the variables (used for inputs and outputs) for one program in start. In declaration we have to tell the types of variables also. If we have more than one types of variables in one program then we have to mention them separately in the start.

(Variable Declarations)

1. int num1, num2, num3;

2. float price1, price2;

3. char gender;

(Constant Declaration) 1. const int week,per_year=52, days_per_week=7;

The difference in variables and constants is, the value of variable can be changed within a program but the value of constant can’t be changed within a program.

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AVAILABLE DATA TYPES IN CType1 Length Range

int 16 bits -32768 to 32767

float 32 bits 1e-38 to 1e+38

char 8 bits -128 to 127

unsigned int 16 bits 0 to 65535

long int 32 bits -2147483648 to 2147483647

unsigned long 32 bits 0 to 4294967295

double 64 bits 1.7*(10**-308) to 1.7*(10**+308)1.7*(E-308) to 1.7*(E+308)

long double 80 bits 4.4*(10**-4932) to 1.1*(10**+4932)

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ASSIGNMENT STATEMENTSThe way of storing data in a variable i.e. storage location inside computer memory.E.g.

A = 5; num1 = 15;

ASSIGNMENT OPERATOR

RIGHT

HAND

SIDE

15

15 WILL GO IN num1

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EXPRESSION STATEMENTSThe basic assignment operator is the equal sign ( = ).

Sometimes we use double equal sign ( == ), but that is not like assignment statement, but like comparison.

The statement that contains more than one variable, values or combination of variable & values on the right hand side of an assignment statement is called expression statement e.g.

Salary = 11 + 33; (Value Expression)

Salary = allowance + bvar (Variable Expression)

Salary=salary * 12 + bvar; (Variable & Value Expression)

EXPRESSION

EXPRESSION

EXPRESSION

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DATA TYPE FORMAT SPECIFIERSData Type Format Specifiers

int %i , %dfloat %fchar %c

double %dlong int %li

These format specifiers we use in Input / Output statements.

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OUTPUT STATEMENT printf(“”);printf(“Welcome at KIC”); To display

simple textprintf(“Welcome \n at KIC”); Start new

line “\n”printf(“Welcome \t at KIC”); Give space

b/w text “\t”printf(“Result= %i ”, res); Displays

variable valueprintf(“%i %i”, rate1, rate2); Display

multiple variableprintf(“%6i%6i%6i”, rate1, rate2, total);

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FORMAT SPECIFIERS FIELD WIDTHField: the place where a value is displayedField width: the number of characters a value

occupies including any leading spacesprintf(“%6i%6i%6i”, rate1, rate2, total);

Field Width = 6

9800 240 10040

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SAMPLE PROGRAM#include <stdio.h>void main(){ int field_one, field_two; field_one = 1234; field_two = field_one - 6757; printf(“%i%i\n", field_one, field_two); printf("%6i%6i\n", field_one, field_two); printf("%4i%4i\n", field_one, field_two);}

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SAMPLE PROGRAM OUTPUTThe results shown to the monitor screen should be on three lines without any kind of comments:1234-5523

1234 -55231234-5523

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FLOATING POINTUse the keyword float to declare float

variablesUse the float data type when you know the

variable will hold values that has decimal point.

The range of float numbers is from 1e-38 to 1e38

To display float numbers use %fprintf(“%9.3f”, 12345.123);

12345.123

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FLOATING POINTShow the output obtained from:printf(“%9.3f%2.2f\n”, 41.57, 79.341);

printf(“%7.4f%10.2f\n”, 325.7, 324.125);325.7000 324.13

41.57079.34

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DOUBLE NUMBERSThe keyword double is used to define double numbers

Double values have the range 1E-308 to 1E+308CHARACHTERS

Characters are letters and symbolsWhen you need to store letters, use character

variable.Use the keyword char to declare character

variables.Character variables can store only one letter e.g.

A or B or C etc.