Learn Guard Clauses | Advanced Conditional Techniques

When writing C functions, you often need to handle special or error cases before performing the main logic. A guard clause is a programming pattern where you check for these special cases at the beginning of a function and immediately return if the condition is met.

guard_clause_example.c


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void process(int value) {
    if (value < 0) return; // guard clause: exit early if input is invalid
    // main logic continues here
    // ...
}

This approach can make your code easier to read and maintain, as it prevents deep nesting and keeps the main logic clear and focused.

main.c


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#include <stdio.h>

void print_square_if_positive(int n) {
    if (n <= 0) {
        return; // Exit early if input is not positive
    }
    
    int square = n * n;
    printf("Square of %d is %d\n", n, square);
}

int main() {
    print_square_if_positive(5);   // Valid input
    print_square_if_positive(-3);  // Invalid input
    return 0;
}

Without it, your function becomes deeply nested, harder to read, and more difficult to maintain.

validate_and_compute.c


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#include <stdio.h>

void print_square_if_positive(int n) {
    if (n > 0) {
        int square = n * n;
        printf("Square of %d is %d\n", n, square);
    } else {
        return;
    }
}

int main() {
    print_square_if_positive(5);   // Valid input
    print_square_if_positive(-3);  // Invalid input
    return 0;
}

By applying this pattern consistently, your functions become simpler, clearer, and less prone to hidden bugs.

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Section 3. Chapter 3

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