Question

C++中怎么判断一个字符串是否为空

Answer 1

if(0 == a||0 == *a){ //一种是直接空指针，一种是内容为空
//xxx
}

Answer 2

#include <iostream.h>
#include <string.h>

int main()
{
char ch[]="book";
char *p="";

int len1,len2;
len1=strlen(ch);
if(len1!=0)
cout<<" \nnot null.";
else
cout<<"\n is null";

len2=strlen(p);
if(len2!=0)
cout<<"\nnot null.";
else
cout<<"\n is null";

return 0;
}

Answer 3

首字符是否为'\0' .

Answer 4

判断它的第一个字节是否为0