输入一串字符，统计数字，字母，空格，其他字符的个数?为什么我程序运行有警告不知道原因，望指教

Question

[Error] C:\Users\杨欢\Documents\C-Free\Temp\未命名1.cpp:12: error: ISO C++ forbids comparison between pointer and integer   这是错误提示

#include<stdio.h>

int main()

{ int i,a=0,b=0,c=0,d=0,e,f;

char s1[i]; 

gets(s1);

for(i=0;s1[i]!="/0";i++)

{

if('A'<=s1[i]<='Z'&&'a'<=s1[i]<='z')

{a=a++;}

if(0<=s1[i]<=9)

{b=b++;}

if(s1[i]==" ")

{c=c++;}

}

printf("%d %d %d",a,b,c);

 }这是我 的程序

Answer 1

                if(s1[i]==' ')//要用单引号括起来一个空格。if('A'<=s1[i]<='Z'&&'a'<=s1[i]<='z')//没有这种逻辑运算要修改为 if(s1[i]>='A'&&s1[i]<='Z'||s1[i]>='a'&&s1[i]<='z') 同理if(0<=s1[i]<=9)修改为if(s1[i]>='0'&&s1[i]<='9')//注意这里应该是数字字符for(i=0;s1[i]!="/0";i++)这里也有错for(i=0;s1[i]!='\0';i++)