检查该值是否为十进制数字(而不是字符形式的数字)

int digits = 220; // Or scanf("%d", digits); Or any way to take the input from user
if(digits == `integer number`){
   // do things
}else{
   // do things
}

int digits = 220; // Or scanf("%d", &digits);

就这样，你完了！

或者，如果scanf("%d", &digits)返回1，则整数已被成功读取并以数字形式存储。

注意声明int digits确保只有整数值可以存储在digits中。

因此：

int digits;
if (scanf("%d", &digits) == 1) {
  // Integer was read successfully from stdin and assigned to digits
} else {
  // Integer was not read. No value was assigned to digits
}