题目：输入一个字符串，统计字符串中大、小写字母，数字及其他字符出现的次数

代码解释：

#include <stdio.h>
int main() {
  char chuan[1000];
  scanf("%s", chuan);
  int big = 0, small = 0, number = 0, other = 0, i = 0;
  for (; chuan[i] != 0; ++i) {
    if (chuan[i] > 'A' && chuan[i] < 'Z') {
      big = big + 1;
      continue;
    }
    if (chuan[i] > 'a' && chuan[i] < 'z') {
      small = small + 1;
      continue;
    }
    if (chuan[i]>='0'&&chuan[i<='9']) {
      number = number + 1;
      continue;
    }
    other = other + 1;
  }
  printf("%d ", big);
  printf("%d ", small);
  printf("%d ", number);
  printf("%d\n", other);
  return 0;
}