Question

我正在尝试制作牛顿第二定律计算器，当我输入计算值时，什么也没发生。我不确定它们是否没有返回到主函数或什么。我想做的是让用户输入一个字符，然后该字符被包含switch语句的函数采用，在switch语句的情况下，该函数将对执行算术的函数进行函数调用，然后这些函数将一个值返回给开关功能和开关功能将返回一个值给主功能，然后将其打印到屏幕上。

// Newtons2ndlaw.cpp : This file contains the 'main' function. Program 
execution begins and ends there.
//

#include "pch.h"
#include <stdio.h>
#include <stdlib.h>
#include<iostream>

void varselect(char, float *);

void force(float *);

void acceleration(float *);

void mass(float *);

int main()


{

    float eqvalue;
    char operation;

    printf("Welcome to Newtons 2nd law solver!\n");

    system("PAUSE");

    printf("Would you like to solve for a Force, Acceleration or Mass?\nType 'F'(for force), 'A'(for acceleration), 'M'(for mass) to select a variable\n");

    scanf_s("%c", &operation,1);
    if (operation == 'f' || operation == 'F' || operation == 'a' || operation == 'A' || operation == 'm' || operation == 'M')           //logic for determing what the user entered
    {}
    else
    {
        printf("Please enter a valid character.");
    }

     varselect(operation,&eqvalue);             //function call to receive float value from varselect function

     if (operation == 'f' || operation == 'F')              //{
     {
         printf("The force = %f",eqvalue);
     }
                                                                //this block determines what character string to display with calculated float value                                    
     else if (operation == 'a' || operation == 'A')                         
     {
         printf("The acceleration = %f", eqvalue);
     }

     else if (operation == 'm' || operation == 'M')
     {
         printf("the Mass = %f", eqvalue);
     }
}                                                           //}

void varselect(char x, float *j)                            
                                                                    //this function recieves the user inputed char value and returns the calculated float value to function call. 
{                                                                   //switch allows program to "understand" users unwillingness to press shift before a,f,m like printf statement tells them to do.
    switch (x)                                                      // also allows each variable to call its own function.
    {
    case 'f':
        float getval;
        force(&getval);
        *j = getval;
        return;
        break;
    }

    switch (x)
    {
    case 'F':
        float getval;
        force(&getval);
        *j = getval;
        return;
        break;
    }

    switch (x)
    {
    case 'a':
        float getval;
        acceleration(&getval);
        *j = getval;
        return;
        break;
    }

    switch (x)
    {
    case 'A':
        float getval;
        acceleration(&getval);
        *j = getval;
        return;
        break;
    }

    switch (x)
    {
    case 'm':
        float getval;
        mass(&getval);
        *j = getval;
        return;
        break;

    }

    switch (x)
    {
    case 'M':
        float getval;
        mass(&getval);
        *j = getval;
        return;
        break;
    }
    return;
}

void force(float *fma)                                      
{
    float acceleration, mass;

    printf("Enter a value for 'Mass', then 'Acceleration'.\n\n");
    scanf_s("%f\n%f\n", &mass, &acceleration, 2);

        *fma = mass * acceleration;

        return;

}

void acceleration(float *afm)
{                                                                                                                           //functions to take input from user and return float to varselect function
    float force, mass;

    printf("Enter a value for 'Force', then 'Mass'.\n\n");
    scanf_s("%f\n%f\n", &force, &mass, 1);

        *afm = force / mass;

    return;

}

void mass(float *fam)
{
    float force, acceleration;

    printf("Enter a value for 'Force', then 'Acceleration'.\n\n");
    scanf_s("%f\n%f\n", &force, &acceleration, 1);

    *fam = force / acceleration;

    return;
}

Answer 1

我认为它与您的代码有关...我能说的是，如果您有一个int或double或float函数，则其作用与void相同。您输入了所需的参数，例如牛顿第二定律或您需要的参数。在此可以添加切换功能。切换之后，您将返回输出。在{}之后的切换之后，将return输出或要返回的变量的名称放入。要使其在控制台上，您只需像这样进行操作： std :: cout <<（函数名）输出（/ *函数参数中的变量或其他* / 13，4.0f）<

程序不返回值给函数

1 个答案: