if Statement

if statement is a basic control flow structure of C programming language. if statement is used when a unit of code need to be executed by a condition true or false. If the condition is true, the code in if block will execute otherwise it does nothing. The ifstatement syntax is simple as follows:

1.if(condition){

2./* unit of code to be executed */

3.}

C programming language forces condition must be a boolean expression or value. ifstatement has it own scope which defines the range over which condition affects, for example:

01./* all code in bracket is affects by if condition*/

02.if(x == y){

03.x++;

04.y--;

05.}

06./* only expression x++ is affected by if condition*/

07.if(x == y)

08.x++;

09.y--;

In case you want to use both condition of if statement, you can use if-else statement. If the condition of if statement is false the code block in else will be executed. Here is the syntax of if-else statement:

1.if(condition){

2./* code block of if statement */

3.}else{

4./* code block of else statement */

5.}

If we want to use several conditions we can use if-else-if statement. Here are common syntax of if-else-if statement:

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01.if(condition-1){

02./* code block if condition-1 is true */

03.}else if (condition-2){

04./* code block if condition-2 is true */

05.}else if (condition-3){

06./* code block if condition-3 is true */

07.}else{

08./* code block all conditions above are false */

09.}

1.if(x == y){

2.printf("x is equal y");

3.}

4.else if (x > y){

5.printf("x is greater than y");

6.}else if (x < y){

7.printf("x is less than y");

8.}


source:cprogramlanguage.net