区分C中的字母和整数 [英] Distinguish between a letter and integer in C

问题描述

请注意，我并不是想像 ctype.h 中的 isalpha() 等函数那样区分单个数字和字母(或其他字符)

Please note that I'm NOT trying to distinguish between a single digit and a letter (or other character) as done by functions like isalpha() in ctype.h

我试图区分整数和字母.

I'm trying to distinguish between an integer and an alphabet.

问题是字母在 C 中也被视为整数，我想不出办法.

The problem is that an alphabet is also treated as an integer in C and I can't think of a way out.

例如:如果输入是字母a，它与'a'相同，即整数97.

eg: if input is the letter a, it is the same as 'a' which is the integer 97.

我需要确定输入是 'a' 还是 97.

And I need to find if 'a' or 97 was the input.

我尝试这样做并意识到它根本行不通.

I tried to do this and realised it simply couldn't work.

int a;
scanf("%d", &a);
if( (a>='A' && a<='Z') || (a>='a' && a<='z') )
{
   printf("
Alphabet");
}

推荐答案

查看scanf()的返回值

int val;
int chk = sscanf("a", "%d", &val);
if (chk == 1) /* all ok */;
if (chk == 0) /* no assignments */;
if (chk == EOF) /* error */;

或

int val;
int chk = sscanf("97", "%d", &val);
if (chk == 1) /* all ok */;
if (chk == 0) /* no assignments */;
if (chk == EOF) /* error */;

或

int val1, val2, val3;
int chk = sscanf("97 b 99", "%d%d%d", &val1, &val2, &val3);
if (chk == 3) /* all ok */;
if (chk == 2) /* only val1 and val2 were assigned a value */;
if (chk == 1) /* only val1 was assigned a value */;
if (chk == 0) /* no assignments */;
if (chk == EOF) /* error */;

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