Trim

A lightweight, efficient C library for trimming whitespace from strings in-place.

Features

• In-place trimming: Modifies the original string without allocating new memory
• Comprehensive whitespace handling: Removes spaces, tabs, newlines, carriage returns, form feeds, and vertical tabs
• Safe: Includes NULL pointer checking and proper error handling
• Fast: Single-pass algorithm with minimal memory operations
• Standard compliant: Uses standard C library functions only

Installation

Using clib

$ clib install vendethiel/trim.c

Manual Installation

1. Copy trim.c and trim.h to your project
2. Include trim.h in your source files
3. Compile trim.c with your project

API Reference

char *trim(char *str)

Trims leading and trailing whitespace from a string in-place.

Parameters:

• str: Pointer to the null-terminated string to trim. Must not be NULL.

Returns:

• Pointer to the trimmed string (same as input parameter)
• NULL if the input is NULL

Whitespace characters removed:

• Space (' ')
• Tab ('\t')
• Newline ('\n')
• Carriage return ('\r')
• Form feed ('\f')
• Vertical tab ('\v')

Important notes:

• The function modifies the original string
• The input string must be mutable (not a string literal)
• Internal whitespace is preserved
• The function is safe with NULL input

Examples

Basic Usage

#include "trim.h"
#include <stdio.h>

int main(void) {
    char str[] = "  hello world  ";
    printf("Before: '%s'\n", str);    // "  hello world  "
    trim(str);
    printf("After:  '%s'\n", str);    // "hello world"
    return 0;
}

Various Whitespace Types

char str1[] = "\t\n  example  \n\t";
trim(str1);  // Result: "example"

char str2[] = "   only spaces   ";
trim(str2);  // Result: "only spaces"

char str3[] = "no_spaces";
trim(str3);  // Result: "no_spaces" (unchanged)

Edge Cases

char empty[] = "";
trim(empty);  // Result: "" (unchanged)

char spaces[] = "   ";
trim(spaces);  // Result: "" (empty string)

char *null_ptr = NULL;
char *result = trim(null_ptr);  // Result: NULL

Chaining Operations

char str[] = "  example  ";
printf("Trimmed: '%s'\n", trim(str));  // Uses return value directly

Building and Testing

Build Test Suite

make test
make run

Build Examples

make example
make run-example

Clean Build Files

make clean

Format Code

make fmt

Performance Characteristics

• Time Complexity: O(n) where n is the string length
• Space Complexity: O(1) - no additional memory allocation
• Memory Operations: Minimal - only one memmove operation when necessary

Thread Safety

The trim function is thread-safe as long as different threads operate on different strings. It is not safe for multiple threads to call trim on the same string simultaneously.

Error Handling

• NULL input: Returns NULL safely without crashing
• Empty string: Returns the same empty string
• Whitespace-only string: Results in an empty string
• No whitespace: Returns the original string unchanged

Compatibility

• C Standard: C99 and later
• Dependencies: Standard C library only (ctype.h, string.h)
• Platforms: Cross-platform (Windows, Linux, macOS, embedded systems)

Common Use Cases

• Processing user input from forms or command line
• Cleaning data read from files
• Preprocessing strings before parsing
• Normalizing configuration values
• Preparing strings for comparison

License

MIT License - see the license file for details.

Contributing

Contributions are welcome! Please ensure:

• Code follows the existing style (use make fmt)
• All tests pass (make run)
• New features include appropriate tests
• Documentation is updated for API changes

Changelog

v0.0.1

• Initial release
• Basic trim functionality
• Comprehensive test suite
• Full documentation