C修改文件内容
方法是：先读出文件到临时文件，然后修改，删掉源文件，改名。
#include "stdio.h"
main(){
FILE *in=fopen("f:\\test.txt","r");
FILE *out=fopen("f:\\back.txt","w"); /*out是充当临时文件作用*/
int ch=0;
if(!in)
{
printf("cann't open test.txt\n");
exit(1);
}
if(!out)
{
printf("cann't create back.txt\n");
exit(1);
}
/*开始复制*/
while(!feof(in))
{
ch=fgetc(in);
if(ch=='a') ch='p';
fputc(ch,out);
}
fclose(in); fclose(out);
unlink("f:\\test.txt"); /*删除test.txt*/
rename("f:\\back.txt","test.txt"); /*改名*/
printf("ok!!!!!!\n");
}