Strings & Pointers

C Program to Reverse a String Using Pointers

Reverse a null-terminated character array (string) in place using two raw memory pointers without allocating secondary buffers.

C Source Code

Editable code sample with line numbers

Expected Output

When this program is compiled and executed, the terminal outputs:

Original string: ZenCompiler C11
Reversed string: 11C relipmoCneZ

How the Code Works

The function reverse_string accepts a mutable character pointer. The end pointer is initialized to the last valid character before the null terminator ('\0'). In each iteration of the while loop, characters at *start and *end are swapped via temp, and the pointers step inwards until they meet or cross.

Time Complexity

O(N)

Space Complexity

O(1) in-place

Key Takeaways & Best Practices

Strings must be mutable character arrays (char arr[]), not string literals (char *str = "literal"), to avoid segmentation faults.
Pointer arithmetic (start++, end--) modifies memory addresses directly.

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Runnable Code

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C Program to Reverse a String Using Pointers

C Source Code

Expected Output

How the Code Works

Key Takeaways & Best Practices

Master C with ZenCompiler

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C Program to Reverse a String Using Pointers

C Source Code

Expected Output

How the Code Works

Key Takeaways & Best Practices

Master C with ZenCompiler

Related C Examples

C Program to Check Prime Number

C Program for Dynamic Memory Allocation (malloc, realloc, free)

Python Program to Check Prime Number