看看这个程序怎么调试不了

[ruchong001]

#include <stdio.h>
void main()
{
FILE *fp;
char ch='a';
if (fp=fopen("text1","w")==NULL)
{
printf("can not open file\n");
exit(0);
}
fputc(ch,fp);
fclose(fp);


}
C:\Documents and Settings\zhuandchang\11.cpp(6) : error C2440: '=' : cannot convert from 'bool' to 'struct _iobuf *'Conversion from integral type to pointer type requires reinterpret_cast, C-style cast or function-style cast
C:\Documents and Settings\zhuandchang\11.cpp(9) : error C2065: 'exit' : undeclared identifier
Error executing cl.exe.

11.exe - 2 error(s), 0 warning(s)
来帮我看看呀?为什么错误

[NKLoveRene]

加个括号

if   ( (fp=fopen("text1","w")) ==NULL)

[ruchong001]

找到一个错误.还有一个
C:\Documents and Settings\zhuandchang\1.cpp(9) : error C2065: 'exit' : undeclared identifier

[ruchong001]

还有啊,为什么要加括号?不加不行么?

[wuyu637]

#include <stdlib.h>

[wuyu637]

不加括号的话，运算符的优先级不够，不能按照你想的顺序计算。

[visame]

#include   <stdio.h>
#include <stdlib.h>//exit()函数的需要
void   main()
{
FILE   *fp;
char   ch='a';
if   ((fp=fopen("text1","w"))==NULL)//赋值运算符=的优先级那可是相当的低,是倒数几位,所以要加括号
{
printf("can   not   open   file\n");
exit(0);
}
fputc(ch,fp);
fclose(fp);
/*
(fp=fopen("text1","w"))==NULL如果不加括号，就是fp=fopen("text1","w")==NULL
根据运算符优先级：fp=(fopen("text1","w")==NULL)。==先算，运算的结果是bool型常量true/false。
于是变成fp=true;或者fp=false;
于是提示错误，
error   C2440:   '='   :   cannot   convert   from   'bool'   to   'struct   _iobuf   *'Conversion   from   integral   type   to   pointer   type   requires   reinterpret_cast,   C-style   cast   or   function-style   cast
这个错误的意识是说：true/false是bool型，而fp是FILE   *类型，不能进行赋值运算阿！
这个struct   _iobuf   *应该是File *的真正结构吧！
*/

[yang511yang]

#include <stdio.h>
void main()
{
FILE *fp;
char ch='a';
if ((fp=fopen("text1","w"))==NULL)//赋值运算符=的优先级那可是相当的低,是倒数几位,所以要加括号
{
printf("can not open file\n");
return;
}
fputc(ch,fp);
fclose(fp);

[ruchong001]

解释的很精辟啊,我懂了,多谢啊