C语言 如何读取到文件 C 的末尾，fscanf
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How to read until end of file C, fscanf
提问by R. Naired
What i read from a file: a P1/ s/ e/ t etc. / for different line. After specific letters(like 'a') come some data i have to collect so i don't want to use fgets. It doesn't end running. Could you help me, please?
我从文件中读取的内容：不同行的 P1/ s/ e/ t 等/。在特定字母（如“a”）之后，我必须收集一些数据，所以我不想使用 fgets。它并没有结束运行。请问你能帮帮我吗？
char com[21];
fscanf(src,"%s",com);
while(com!=EOF)
{
if(com[0]=='a')
fprintf(dest,"%s 1",com);
if(com[0]=='s')
fprintf(dest,"%s 2",com);
fscanf(src,"%s",com);
}
回答by usr
Simple way is to test if fscanf()succeeded as the loop condition and you don't need a fscanf()before the loop:
简单的方法是测试是否fscanf()成功作为循环条件，并且fscanf()在循环之前不需要 a ：
char com[21];
while(fscanf(src,"%20s",com) == 1)
{
if(com[0]=='a')
fprintf(dest,"%s 1",com);
if(com[0]=='s')
fprintf(dest,"%s 2",com);
}
fscanf()returns the number of items successfully scanned. So, you don't need to check if it' returned EOF.
fscanf()返回成功扫描的项目数。因此，您无需检查它是否已返回EOF。
Note that I changed the format string to avoid buffer overflow. I suggest you use fgets()instead of fscanf()(and remember to take care of newline chars if it matters).
请注意，我更改了格式字符串以避免缓冲区溢出。我建议您使用fgets()而不是fscanf()（如果重要，请记住处理换行符）。
回答by Jay
Please note that fscanfreturns an integerwhich can indicate EOFwhen the End of File is reached. Please refer to the man pages for more detail.
请注意，fscanf返回一个integer可以指示EOF何时到达文件结尾。有关更多详细信息，请参阅手册页。
Your code will have to modified like below:
您的代码必须修改如下：
char com[21];
int ret;
ret = fscanf(src,"%s",com);
while(ret!=EOF)
{
if(com[0]=='a')
fprintf(dest,"%s 1",com);
if(com[0]=='s')
fprintf(dest,"%s 2",com);
ret = fscanf(src,"%s",com);
}
