<ctype.h>头文件中，用来判断一个字符是否为 ASCII 码字符（ASCII 码值在 0~127 之间）。int isascii(int c);
#include <stdio.h>
#include <ctype.h>
int main() {
char str[] = { 'A', 'b', '9', 128, -1, '\0' }; // 包括非 ASCII 字符
for(int i = 0; str[i] != '\0'; i++) {
if(isascii(str[i])) {
printf("'%c' is a valid ASCII character.\n", str[i]);
} else {
printf("Character at index %d is NOT a valid ASCII character.\n", i);
}
}
return 0;
}
输出结果为：
'A' is a valid ASCII character.
'b' is a valid ASCII character.
'9' is a valid ASCII character.
Character at index 3 is NOT a valid ASCII character.
Character at index 4 is NOT a valid ASCII character.
int isascii(int c) {
return (c >= 0) && (c <= 127);
}
这个简单的函数会检查输入字符是否在 ASCII 范围内，并返回相应的真或假值。
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