Fgets（）要求在读取char数组后输入两次

Question

当我在函数isFloat(char array[])中输入任何评估为false 的时，我需要按两次Enter键以保持程序运行。

如果我注释掉fget()命令以外的所有内容要求我按两次输入。可能是什么导致了这个？我正在正确刷新stdin，\n已移除strtok()。 printf()函数会导致问题吗？我已经读过，scanf()和fgets()在一起使用时可能会导致问题。但在这里他们不是。

问题区域

printf("first number: ");
    fgets(input, TEN_THOUSAND, stdin);
    strtok(input, "\n");
    success = isFloat(input);
    if(success)
        firstNum = atof(input);

完整代码：

#include<stdio.h>
#include<stdlib.h>
#include<stdio.h>
#include<string.h>

int isFloat(char array[])
{

int m = 0;
int periodCount = 0;

for(m=0; array[m] != '\000'; m++)
    {
        if(array[m] == '1' || array[m] == '2' || array[m] == '3' || array[m] == '4' || array[m] == '5' || array[m] == '6' || array[m] == '7' || array[m] == '8' || array[m] == '9' || array[m] == '0')
            {
            }
        else
            {
                if(array[m] == '.' && periodCount == 0 && m != 0 && m+1 != '\n')
                    periodCount = 1;
                else
                    return 0;
            }
    }
return 1;
}

void eatLine()
{
    while (getchar() != '\n');
}

int main()
{

double firstNum = 0.0;
double secondNum = 0.0;
double totalNum = 0.0;
int success = 0;
int TEN_THOUSAND = 10000;
char input[TEN_THOUSAND];

//Outputs assignment header
printf("CS201 - Lab 2 - Number Adder\n\n");

printf("first number: ");
fgets(input, TEN_THOUSAND, stdin);
strtok(input, "\n");
success = isFloat(input);
if(success)
    firstNum = atof(input);

while(!success)
{
    eatLine();
    //The one is for testing purposes
    printf("-- bad input --\n");
    printf("first number: ");
    fgets(input, TEN_THOUSAND, stdin);
    strtok(input, "\n");
    success = isFloat(input);
    if(success)
        firstNum = atof(input);
}

printf("second number: ");
fgets(input, TEN_THOUSAND, stdin);
strtok(input, "\n");
success = isFloat(input);
if(success)
    secondNum = atof(input);

while(!success)
{
    eatLine();
    //The one is for testing purposes
    printf("-- bad input --\n");
    printf("second number: ");
    fgets(input, TEN_THOUSAND, stdin);
    strtok(input, "\n");
    success = isFloat(input);
    if(success)
        secondNum = atof(input);
}

//adds the numbers
totalNum = firstNum + secondNum;

//Solves ugly formatting problem by firstly including a newline 
//after the input is garnered. then it outputs firstNum and totalNum 
//in a field of 11 spaces with a newline terminator. This decrements 
//11 to 10 on the secondNum line to compensate for the space that the + takes up.
printf("\n%11.2f\n", firstNum);
printf("%s%10.2f\n", "+", secondNum);
printf("-----------\n");
printf("%11.2f\n\n", totalNum);

return 0;
}

Answer 1

  

当我在函数isFloat(char array[])中输入任何评估为false的内容时，我需要按两次Enter键以保持程序运行。

那是因为你有一行代码要求你输入一行文字。

while(!success)
{
   eatLine(); // Culprit