[英]c check integer
I'm finding a function to check digit in c, is isdigit only check 0-9 ? 我正在寻找一个函数来检查c中的数字,isdigit仅检查0-9吗? how about 10-99999?
10-99999怎么样?
i have an integer, eg 22, i want to check is it valid? 我有一个整数,例如22,我要检查是否有效?
any ideas? 有任何想法吗? thanks~
谢谢〜
isdigit
et. 等
isdigit
等 al are for checking characters. al用于检查字符。 10-99999 is no longer a single character.
10-99999不再是单个字符。 If you want to check that the string "8382820" is numeric, you have (at least) 3 options:
如果要检查字符串“ 8382820”是否为数字,则(至少)有3个选项:
isdigit
on each character (failing if one of them isn't) isdigit
(如果其中一个不是,则失败) "^[0-9]+$"
should do the trick, but not very practical in C) "^[0-9]+$"
应该可以解决问题,但在C语言中不太实用) strtol
and check that the end pointer is the null terminator. strtol
并检查结束指针是否为空终止符。 Here's an idea of how to use strtol: 这是有关如何使用strtol的想法:
char* myString = "9823872";
char* endPtr = NULL;
long int myInt = strtol(myString, &endPtr, 10);
if(endPtr && *endPtr != '\0')
{
fprintf(stderr, "Sorry, that's not a valid number\n");
exit(1);
}
There are probably other clever answers involving scanf or atoi, but I'll just leave it at this for now. 可能还有其他涉及scanf或atoi的聪明答案,但我现在就将其保留下来。
The isdigit()
function checks one character at a time. isdigit()
函数一次检查一个字符。 If you want to check more than one character from a string, loop over the characters in the string and call isdigit()
on each one. 如果要检查一个字符串中的多个字符,请遍历字符串中的字符,然后对每个字符调用
isdigit()
。
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