代码缺少库：块

Question

Recently picked up programming again. I am a beginner. I took one class a while back, but am now trying to compile and run a program I have on flash that worked fine in class using Dev C++. I am using the latest version of Code::Blocks at home now.

Here is the program code as follows for a simple calculator program:

/* This program adds, subtracts, multiplies, and divides two integers. */

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

// Function Declarations
int getOption(void);
void getData (int* a, int* b);
float calc   (int option, int num1, int num2);

float add  (float num1, float num2);
float sub  (float num1, float num2);
float mul  (float num1, float num2);
divn (float num1, float num2);

void printResult (float num1, float num2, float result, int option);

int main (void)
{
// Local Declarations
int done = 0;
int option;
int num1;
int num2;
int result;

// Statements
while (!done)
{
    option = getOption();
    if (option == 5)
    done = 1;
    else
    {
        do
            {
                printf("\n\nEnter two numbers: ");
                scanf("%f %f", &num1, &num2);
                if (option == 4 && num2 == 0)

                {
                    printf("\a\n *** Error *** ");
                    printf("Second Number cannot be 0\n");
                    } //if

                    } while (option == 4 && num2 == 0);

                    switch (option)
                    {
                        case 1: result = add  (num1, num2);
                        break;
                        case 2: result = sub  (num1, num2);
                        break;
                        case 3: result = mul  (num1, num2);
                        break;
                        case 4: result = divn (num1, num2);
                        } // switch

                printResult (num1, num2, result, option);
            } // else option != 5
        } // while

        printf("\nThank you for using Calculator.\n");
        return 0;
    } // main

/* ========================= getOption ===================================
    This function shows a menu and reads the user option.
        Pre     nothing
        Post    returns a valid option */

int getOption (void)
{
// Local Declarations
int option;

// Statements
do
{
    printf("\n******************");
    printf("\n*      Menu      *");
    printf("\n*                *");
    printf("\n*  1.  ADD       *");
    printf("\n*  2.  SUBTRACT  *");
    printf("\n*  3.  MULTIPLY  *");
    printf("\n*  4.  DIVIDE    *");
    printf("\n*  5.  QUIT      *");
    printf("\n*                *");
    printf("\n******************");

    printf("\n\n\nPlease type your choice ");
    printf("and press the return key : ");
    scanf("%d", &option);

    if (option < 1 || option > 5);
    printf("Invalid option. Please re-enter.\n");

 } while (option < 1 || option > 5);
    return option;
} // getoption

Getting the following build errors when I try to compile:

C:\Users\Christopher\SkyDrive\School\Programming\Practice Stuff\complete calculator.o:complete calculator.c|| undefined reference to `add'|
C:\Users\Christopher\SkyDrive\School\Programming\Practice Stuff\complete calculator.o:complete calculator.c|| undefined reference to `sub'|
C:\Users\Christopher\SkyDrive\School\Programming\Practice Stuff\complete calculator.o:complete calculator.c|| undefined reference to `mul'|
C:\Users\Christopher\SkyDrive\School\Programming\Practice Stuff\complete calculator.o:complete calculator.c|| undefined reference to `divn'|
C:\Users\Christopher\SkyDrive\School\Programming\Practice Stuff\complete calculator.o:complete calculator.c|| undefined reference to `printResult'|
||=== Build finished: 5 errors, 0 warnings (0 minutes, 0 seconds) ===|

I believe the errors are not because of code errors (I KNOW the code worked before) but because I am using Code::Blocks instead of Dev C++ now, I need to reference a different library but have no idea which library i need.

And help would be greatly appreciated.

Answer 1

You can clearly see that add, sub, mul, divn, printResult are declared but not defined. Therefore, in order to use them you would need to define them. Also, your code is inaccurate:

1. Takes two int as input, but perform all of the operations on float ...
2. Secondly, as stated above you do not define your functions anywhere but proceed to use them.
3. Finally, some of the function declared ( getOption, getData & calc ) are defined, why not do the same for the arithmetic functions and the printResult.

Therefore, it is not because of a missing library but because the function were declared but not defined. Or you might need to link another file containing the definition if such is the case.

-Dany