posix C新接触的库函数

1.backtrace与backtrace_symbols       打印栈信息,在调试器不能使用的情况下，有用。

int backtrace(void **buffer, int size);
char **backtrace_symbols(void *const *buffer, int size);

void backtrace_symbols_fd(void *const *buffer, int size, int fd);

示例代码：

void print_stack(void)
{
    static char stack_info[MAXLINE];
    const int max_depth = 200;
    void *func_array[max_depth];

    int nptrs = backtrace(func_array, max_depth);
    printf ( "there are %d pointers\n", nptrs);

    char **strings = backtrace_symbols(func_array, nptrs);
    char *stack_ptr = stack_info;
    int  nlen = 0;

    if (strings)
    {
        int index = 0;
        memset(stack_info, '\0', sizeof(stack_info));
        for (; index < nptrs; ++index)
        {
            nlen = sprintf(stack_ptr, "%s\n", strings[index]);
            stack_ptr += nlen;
        }

        //  free(strings);
    }
    else
    {
        printf ( "no stack information\n" );
    }
    printf ( "the core dump stack info:\n\n%s", stack_info);


    return;
}

2.Posix 正则表达式

//编译正则表达式,成功返回0，失败返回错误码
int regcomp(regex_t *preg, const char *regex, int cflags);

 //执行，pmatch与nmatch组合用来存储匹配的子串的位置.

int regexec(const regex_t *preg, const char *string, size_t nmatch, regmatch_t pmatch[], int eflags);

size_t regerror(int errcode, const regex_t *preg, char *errbuf, size_t errbuf_size);

void regfree(regex_t *preg);

示例代码：

static int match(const char *str, const char *regexp)
{
    if ((!str) || (!regexp))
        return 0;

    int ret = 0;
    regex_t reg;
    static const int flag = REG_EXTENDED | REG_ICASE | REG_NEWLINE;
    static char  errbuf[128];
    int res = regcomp(&reg, regexp, flag);
    if (res) {
        regerror(res, &reg, errbuf, sizeof(errbuf));
        printf("compile the [%s] failed for %s\n", regexp, errbuf);
        goto out;
    }

    regmatch_t matches[4];
    res = regexec(&reg, str, 4, matches, 0);
    if (!res) {
        regmatch_t *mp = &matches[0];
        while (mp->rm_so != -1)
        {
            int k = 0;
            for (k = mp->rm_so; k < mp->rm_eo; ++k)
            {
                putchar(str[k]);
            }
            printf ( "\n" );
            ++mp;
        }
        ret = 1;
        printf ( "match\n" );
    }
    else
        printf ( "doesn't match\n" );

out:
    regfree(&reg);
    return ret;
}