[英]Converting a char* to unsigned int in C safely?
I wrote a pretty simple function to perform this conversion in C. Is it perfectly safe?我编写了一个非常简单的函数来在 C 中执行这种转换。它完全安全吗? if not, what are the other ways?
如果没有,还有什么其他方法?
EDIT: I rewrote the function to add more effective error checks.编辑:我重写了函数以添加更有效的错误检查。
#define UNLESS(x) if (!(x))
int char_to_uint(const char *str, unsigned int* res)
{
/* return 0 if str is NULL */
if (!str){
return 0;
}
char *buff_temp;
long long_str;
/* we set up errno to 0 before */
errno = 0;
long_str = strtol(str, &buff_temp, 10);
/* some error and boundaries checks */
if (buff_temp == str || *buff_temp != '\0' || long_str < 0){
return 0;
}
/* errno != 0 = an error occured */
if ((long_str == 0 && errno != 0) || errno == ERANGE){
return 0;
}
/* if UINT_MAX < ULONG_MAX so we check for overflow */
UNLESS(UINT_MAX == ULONG_MAX){
if (long_str > UINT_MAX) {
return 0;
} else {
/* 0xFFFFFFFF : real UINT_MAX */
if(long_str > 0xFFFFFFFF){
return 0;
}
}
}
/* after that, the cast is safe */
*res = (unsigned int)long_str;
return 1;
}
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