Trim a string in C

strtrim.c

/**
 * @brief This function removes the blank spaces from a
          string that are at the beginning and end of it.
 *
 * @details The string is traversed from the beginning
 *          until the first character is found, which
 *          will be set as the trimmed string beginning.
 *          Thereafter, the same is done from the end of
 *          the string until the last character is found,
 *          which will be set as the trimmed string end.
 *          At the end of the trimmed string, the special
 *          end-of-string character is placed.
 *          If the given string is empty, it is returned
 *          as it came.
 *
 * @param str String to be trimmed.
 *
 * @return The trimmed string.
 */
char *strtrim(char *str)
{
    while ((*str == ' ') || (*str == '\t') || (*str == '\n'))
        str++;

    if (*str == 0)
        return str;

    char *end = str + strlen(str) - 1;

    while ((end > str) && ((*end == ' ') || (*end == '\t')))
        end--;

    end[1] = '\0';

    return str;
}