What is the usage of if statement in c language

C language if statement usage: 1. [if (expression) statement] means if the expression is true, the printf statement will be executed; 2. [if (expression) statement 1 else statement 2] means if [x>y] is true, then the statement printf is executed and else is skipped directly.

C language if statement usage:

1. if (expression) statement

For example:

if（x>y）printf("%d",x);

At this time, if the expression is true, the printf statement is executed.

2. if (expression) statement 1 else statement 2

For example:

if（x>y)printf("%d",x);
else printf("%d",y);

At this time, if x>y is true, Then execute the statement printf("%d",x), then skip the else directly, and also skip the statement printf("%d",y) to execute the subsequent statements.

If x>y is not true and is false, the statement printf("%d",y) will not be executed, but the statement printf("%d",x) will be executed.

3. if (expression 1) statement 1

##else if (expression 2) statement 2

else if (expression 3) statement 3

else if (expression m) statement m

else statement n

At this time, which expression is true, the statement following the if will be run. If expression 3 is true, statement 3 is executed.

In each statement, there can be multiple statements, but braces need to be added

Example:

if(x>y){printf("%d",x);break;}

Extended information:

Notes on the use of if statements:

1. There is no semicolon after if (conditional expression).

Generally speaking, if there is "{}", there is no ";". If there is ";", there is no "{}"

2. If the statement controlled by the if statement is a statement, We don’t need to write braces;

If we control more than two statements, we must add braces.

The control body of the if statement without braces is a statement that follows it.

Suggestion: Always add braces. Avoid unnecessary mistakes.

Related learning recommendations:

C video tutorial

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