Conditional Statements

Introduction

Branching chooses which block runs — chained if/else for ranges, switch when matching one integral value against many labels.

Understanding the topic

if / else Execute block when condition is true (non-zero).

switch Match integral expression against case labels; use break and default.

• if / else — Execute block when condition is true (non-zero).
• switch — Match integral expression against case labels; use break and default.

Step-by-step explanation

1. if / else — Execute block when condition is true (non-zero).
2. switch — Match integral expression against case labels; use break and default.

Syntax reference

Syntax reference:

if (condition) { } else { }
switch (expr) { case val: break; default: }

Informative example

Example program:

#include <stdio.h>

int main(void) {
    int marks = 72;
    if (marks >= 90) printf("Distinction\n");
    else if (marks >= 60) printf("Pass\n");
    else printf("Retake\n");
    return 0;
}

Pass

Execution workflow

Best practices

• Enable warnings: gcc -Wall -Wextra -std=c11 source.c -o app
• Give every variable a defined value before it is read.
• Stay inside array bounds — C will not stop you from over-running a buffer.

Common mistakes

• Reading uninitialized storage — behavior is undefined.
• Dismissing compiler warnings instead of fixing root causes.
• Ignoring NULL returns from malloc, fopen, and similar APIs.

Hands-on exercise

Practice problems:

• Grade calculator with if-else
• Menu driven program with switch

Summary

Conditional Statements in C — if/else chains and switch for branching.