QUESTION 03 · Selection

When does the body of an if statement execute?

2 marks

Answer

It executes when the controlling expression compares unequal to zero.

Zero means false; a non-zero value means true.
When the condition is false, control moves to the statement after the if.

Explain the simple if statement with syntax and an example.

5 marks

Answer in brief

The simple if statement executes a statement or block only when a condition is true.

Syntax

if (condition) {
    /* statements executed when true */
}

Working

Evaluate the condition.
If it is non-zero, execute the body.
If it is zero, skip the body. Continue after the if statement in either case.

Example explanation

Suppose a student receives a certificate when marks are at least 90. For marks = 92, marks >= 90 is true, so the certificate message is printed. For marks = 70, that message is skipped. The final message still prints because it is outside the if block.

Important points

Use braces for a multi-statement body and preferably for a single statement too. Write == to test equality and = to assign a value. Do not put an accidental semicolon after if (condition): that creates an empty body, and a following block executes independently. An if statement makes a decision once; it does not repeat its body. For this fixed-size example, the comparison and optional message require constant work, O(1).

Flowchart

Control flow for if with labelled true and false paths. — Explain the simple if statement with syntax and an example. · Download diagram

C program and output

Download .c Open compiler

/* CodeBhavya | PPS AR25 | Learning example */
#include <stdio.h>
int main(void)
{
    int marks = 92;
    if (marks >= 90) {
        puts("Certificate awarded");
    }
    puts("Check complete");
    return 0;
}

Sample input and output

This example uses values already written in the program.

Output

Certificate awarded
Check complete