safeString

safeString is a small header which comprises several functions intended to perform common operations with C strings in an easier and safer way. It also contains equivalent macros that provide a simpler interface. All functions that involve string modification guarantee that the result will be a valid string regardless of the input string size.

How to use

Include safeString.h in your code. That's it.

All functions and macros return 1 in case of a correct execution, or 0 otherwise (except strClear), so it is easy to test whether the operation has been done as intended.

Note that char* input parameters must not contain an uninitialized pointer, but an array. Also note that the size of a dynamic array can not be obtained by using sizeof() function, so it must be set explicitly.

Functions

• void strClear(char* str, int size): Fills str with \0 within size, thus making a string of length 0.
• int isStr(char* str, int size): Checks if str is a valid string within size. Returns 0 otherwise.
• int isEqual(char* str1, char* str2): Returns 1 if str1 is equal to str2, or 0 otherwise. Both str1 and str2 must be valid strings.
• int safeStrCpy(char* dest, char* src, int size_dest): Copies the maximum possible characters of src string into dest. Returns 1 if the entire src string has been copied, or 0 otherwise. src must be a valid string.
• int safeStrCat(char* dest, char* src, int size_dest): Concatenates the maximum possible characters of src string after dest string. Returns 1 if the entire src string has been concatenated, or 0 otherwise. Both src and dest must be valid strings.
• int safeStrLen(char* str, int size): Returns the number of characters of str not counting the final '\0'. If str is not a string, returns 0.

Macros

These macros are compatible only with static strings. They provide a simpler interface for the functions above without the need of size information.

• STR_CLEAR(str)
• IS_STR(str)
• IS_EQUAL(str1, str2)
• SAFE_STR_CPY(dest, src)
• SAFE_STR_CAT(dest, src)
• SAFE_STR_LEN(str)

Dependencies

The only requirement for safeString is string.h, which should be already installed of most C environments.

Example of use

A more comprehensive code can be found on test/example.c

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

int main(void)
{
    char str1[] = "Hello";
    char str2[] = ", world";
    char small[10];
    char large[100];

    STR_CLEAR(small);
    SAFE_STR_CAT(small, str1);
    SAFE_STR_CAT(small, str2);

    SAFE_STR_CPY(large, str1);
    SAFE_STR_CAT(large, str2);

    printf("small: %s\nlarge: %s\n", small, large);

    return 0;
}