虽然scanf!= EOF或scanf == 1？

Question

Ceteris paribus(格式良好的数据,良好的缓冲实践以及什么不是),是否有理由为什么我更喜欢循环而返回scanf为1,而不是!EOF？我可能已经在某个地方读过这个,或者其他什么,但我也可能错了.其他人怎么想？

Answer 1

scanf返回成功转换的项目数...或出错时的EOF.因此,以有意义的方式对条件进行编码.

scanfresult = scanf(...);
while (scanfresult != EOF) /* while scanf didn't error */
while (scanfresult == 1) /* while scanf performed 1 assignment */
while (scanfresult > 2) /* while scanf performed 3 or more assignments */

举例说明

scanfresult = scanf("%d", &a);
/* type "forty two" */
if (scanfresult != EOF) /* not scanf error; runs, but `a` hasn't been assigned */;
if (scanfresult != 1) /* `a` hasn't been assigned */;

编辑:添加了另一个更人为的例子

int a[5], b[5];
printf("Enter up to 5 pairs of numbers\n");
scanfresult = scanf("%d%d%d%d%d%d%d%d%d%d", a+0,b+0,a+1,b+1,a+2,b+2,a+3,b+3,a+4,b+4);
switch (scanfresult) {
case EOF: assert(0 && "this didn't happen"); break;
case 1: case 3: case 5: case 7: case 9:
    printf("I said **pairs of numbers**\n");
    break;
case 0:
    printf("What am I supposed to do with no numbers?\n");
    break;
default:
    pairs = scanfresult / 2;
    dealwithpairs(a, b, pairs);
    break;
}