我正在抓取用户的一些标准输入,如果用户按 CTRL + D ,我想显示错误并终止程序。我想也许我的问题可能与被困在一个while循环中有关;
int readInput(){
char buff[10];
int count = 0;
int counter;
printf("Enter random number: ");
fgets(buff, 10, stdin);
if ((int) strtol(buff, NULL, 10) == 0){
printf("Error reading number. \n");
return 0; //This will get hit if the user presses CTRL+D at this input.
}
counter = atol(buff);
while (count < counter){
printf("Enter a label: ");
fgets(buff, 10, stdin);
if ((int) strtol(buff, NULL, 10) == 0){
printf("Error reading label");
return 0; //This will not get hit if the user presses CTRL+D at this input, but why?
//I've also tried assigning a variable to 0, breaking out of the loop using break; and returning the variable at the end of the function but that also does not work.
//the rest of the while loop continues even if user hit CTRL+D
printf("Enter Value: " );
fgets(buff, 10, stdin);
//..rest of while loop just gets other inputs like above
count++;
}
//termination happens in main, if readInput returns a 0 we call RETURN EXIT_FAILURE;
我不明白为什么在第一次输入时如果用户按下 CTRL + D ,程序会做出相应的响应,但第二次完全忽略它。
答案 0 :(得分:8)
在Linux上, Ctrl + D 生成EOF
,因此您需要每次都检查fgets()
的返回值。遇到EOF
时,fgets()
返回空指针
if (fgets(buff, 10, stdin) == NULL)
print_error();