Question

我有一个创建程序的任务，询问用户他们想要转换的温度然后转换它，但我的if语句不起作用。

这是我的代码：

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

int main(void) {
//Declare Variables
float ce; //Celcius
float fa; //Fahrenheit
char in; //Input form user
float go; //If a loop should keep running

//Ask the user what they would like to convert
printf("Would you like to convert from Celsius 'C' or Fahrenheit 'F'?\n");

//Get the input from the user
scanf("%d", &in);

//Start the Loop
go = 1;
while (go == 1) {
    if (in == 'F')  { //If the user wants to convert from Fahrenheit
        //Stop the loop
        go = 0;

        //Ask the user the temperature they would like to convert
        printf("What temperature F would you like to convert to C?\n");

        //Get the input from the user
        scanf("%d", &fa);

        //Crunch the Numbers
        ce = ((fa - 32)/1.8);

        //Print the answer
        printf("The temperature in Celcius is %lf\n", ce);

    } else if (in == 'C') { //If the user wants to convert from Celcius
        //Stop the loop
        go = 0;

        //Ask the user the temperature they would like to convert
        printf("What temperature C would you like to convert to F?\n");

        //Get the input from the user
        scanf("%d", &ce);

        //Crunch the Numbers
        fa = (32 + (ce * 1.8));

        //Print the answer
        printf("The temperature in Fahrenheit is %lf\n", fa);

    } else {
        //make sure the loop will continue running
        go = 1;

        //Print an error message
        printf("That is an invalid input, please enter either a 'C' of 'F'\n");

        //Take the input again
        scanf("%d", &in);
    }
}

//End the program
return 0;

}

无论我输入什么，它都会继续回来“这是一个无效的输入......”

如何让我的if语句起作用？我也试过strcmp只得到一个“指针和整数之间的比较”错误。这应该是一个相当简单和基本的程序，但我无法让它工作。

Answer 1

问题：

在您的代码in中声明为char，但您在scanf()中使用了错误的格式说明符，即%d，同时扫描in .. < / p>

scanf("%d",&in)

<强>解决方案：

以避免使用%c作为scanf()

中的格式说明符进行扫描

scanf(" %c",&in)

注意：我已space %c前面\n消耗可能来自换行符（scanf()）的空格以前的scanf()陈述结束

在scanf()中，您传递的所有参数都是指针，并且必须传递与该地址中存在的变量类型匹配的确切格式说明符。

要详细了解在printf()或currentValue = firstValue; while (endNotYetReached(currentValue)) { currentValue = myFunction(currentValue); }中使用错误的格式说明符时会发生什么情况，请参阅：click

Answer 2

在这种情况下使用Switch（）语句更好。

#include <stdio.h>
main()
{
float c,f,k;
int choice;
printf("Which Scale do you want to convert\n 1.Celsius\n 2.Fahrenheit\n 3.Kelvin");
printf("\n Enter Your Choice: ");
scanf("%d",&choice);
switch(choice)
{
    case 1:  printf("Enter Celsius Temperature: ");
             scanf("%f",&c);
             f=(9*c+32)/5;
             k=c+273;
             printf("\nThe Temperature is %.2f in Fahrenheit and %.2f in Kelvin\n",f,k);
             break;
    case 2:  printf("Enter Fahrenheit Temperature: ");
             scanf("%f",&f);
             c=((5*(f-32))/9);
             k=((5*(f-32))/9)+273;
             printf("\nThe Temperature is %.2f in Celsius and %.2f in Kelvin\n",c,k);
             break;
    case 3:  printf("Enter Kelvin Temperature: ");
             scanf("%f",&k);
             c=k-273;
             f=((9*(k-273))/5)+32;
             printf("\nThe Temperature is %.2f in Celsius and %.2f in Fahrenheit\n",c,f);
             break;
    default: printf("\nError. Please Restart The Program\n");
}

}

Answer 3

检查您需要更改的相应更改。

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

int main(void) {
//Declare Variables
float ce; //Celcius
float fa; //Fahrenheit
char in; //Input form user
float go; //If a loop should keep running

printf("Would you like to convert into Celsius 'C' or Fahrenheit 'F'?\n");

//scanf("%d", &in);
scanf("%c", &in);

go = 1;
while (go == 1) {
    if ((in == 'F') || (in == 'f'))  { //If the user wants to convert from Fahrenheit
        //Stop the loop
        go = 0;

        //Ask the user the temperature they would like to convert
        //printf("What temperature F would you like to convert to C?\n");
        printf("What temperature F would you like to convert to C?\n");

        //Get the input from the user
        scanf("%f", &fa);

        //Crunch the Numbers
        ce = ((fa - 32)/1.8);

        //Print the answer
        printf("The temperature in Celcius is %lf\n", ce);

    } else if ((in == 'C')|| (in == 'c')) { //If the user wants to convert from Celcius
        //Stop the loop
        go = 0;

        //Ask the user the temperature they would like to convert
        printf("What temperature C would you like to convert to F?\n");

        //Get the input from the user
        scanf("%f", &ce);

        //Crunch the Numbers
        fa = (32 + (ce * 1.8));

        //Print the answer
        printf("The temperature in Fahrenheit is %lf\n", fa);

    } else {
        //make sure the loop will continue running
        go = 1;

        //Print an error message
        printf("That is an invalid input, please enter either a 'C' of 'F'\n");

        //Take the input again
        scanf(" %c", &in); // because of \n characters entered at the end of previous scanf() statement
    }
}

//End the program
return 0;

}

C程序询问用户是否想要从C转换为F然后执行转换

3 个答案: