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#include<stdio.h>
int main()
{
FILE *fp;
char xp,test;
test=0;
printf("please input a number:\n");
scanf("%d",&test);
if((fp=fopen("zhou.h","w"))!=NULL)
??? fwrite(&test,sizeof(char),1,fp);
fclose(fp);
if((fp=fopen("zhou.h","r"))!=NULL)
fread(&xp,sizeof(char),1,fp);
printf("xp=%d\n",xp);
printf("test=%d\n",test);
fclose(fp);
return 0;
}
please run this program, if input 26, that the value of 'xp' is zero, why?

please try to use the following instruction when open the file:
if((fp=fopen("zhou.h","w+b"))!=NULL) and
if((fp=fopen("zhou.h","r+b"))!=NULL)

I locked voting since this isn't a poll but a question.

The answer imo is that you read an int, store it into a char, write it into a file without checking whether that was a success, then read it back without checking whether THAT was a success either, and then print the result.

Answer is to check more often (after compiling your code it segfaulted here, after putting in the checks it more or less worked, after converting it to longs or ints it just works) and to use the right types for the things you read. You cannot read an int to a char.

cxnew:
thanks, I Know, that must use binary mode to open file.