而有关问题（！EOF） [英] Question about while(!EOF)

问题描述

即时通讯在读值从标准输入，我想直到我已经完成了阅读它一路继续读文件，所以我用

Im reading in values from stdin and I want to keep reading the file until I have completed reading it all the way, so I am using

while(!EOF){ scanf(...) }

不过，code片段似乎并没有做任何事情，

However, the code fragment doesn't seem to do anything,

while(!EOF){


    scanf("%d %d %d %d", &imageWidth, &imageHeight, &safeRegionStart, &safeRegionWidth);

    printf("---imageWidth=%d imageHeight=%d safeRegionStart=%d safeRegionWidth=%d---\n", imageWidth, imageHeight, safeRegionStart, safeRegionWidth);
    totalP = imageWidth * imageHeight ;
    totalSafeP = imageHeight * safeRegionWidth;


    printf("---total # of pixels: %d Total # of safe Pixels: %d---\n\n", totalP, totalSafeP);

    i=1;

    while(i!=totalP)
    {
        i++;
        scanf("%d", &pixel);
        printf("\nValue of pixel %d", pixel);


    }//End for scanning all pixels*/
}//while loop

编辑：我固定它

while(scanf("%d %d %d %d", &imageWidth, &imageHeight, &safeRegionStart, &safeRegionWidth)==4&&!feof(stdin)) { }

！的feof（标准输入）可能是没有必要的。

推荐答案

EOF 只是一个整型常量。在大多数系统中， 1 。 ！ - 1 是假和而（假）韩元'吨做任何事情。

EOF is only an integer constant. On most systems it is -1. !-1 is false and while(false) won't do anything.

你想要的是检查 scanf函数的返回值。 scanf函数返回成功读取项目，并最终数量 EOF 。

What you want is to check the return values of scanf. scanf returns the number of successfully read items and eventually EOF.

这篇关于而有关问题（！EOF）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！