Thread: My program needs troubleshooting...

Well, I tried using the debugger, but I still don't get what I'm doing wrong. Basically, this program is supposed to simulate how much making a long distance call would cost. However, I keep getting a very messed up value. I assume it has something to do with the functions. I'm not sure though. Anyone want to help me out? Thanks

Code:

/*Lab B*/

#include <stdio.h>

int get_gross_cost(int);
int get_net_cost(int, int);
int main() 

{
//Declarations
float discount_rate, regular_rate, tax, net_cost, gross_cost;
int minutes, start_time;
char reply;

//Explanation
printf("This program is designed to calculate how much a long distance call between it's");
printf("peak hours");	

do
{
//User input
printf("\n\nPlease enter what time you would like a call to start (0001-2400): ");
scanf("%i", &start_time);

printf("\nPlease enter the duration of the call in minutes: ");
scanf("%i", &minutes);

//Functions
get_gross_cost(minutes);

get_net_cost(minutes, start_time);

printf("The gross cost of your call is %f", gross_cost);
printf("\nThe net cost of your call is %f", net_cost);

printf("\n\n\nWould you like to try again? <y/n>");
scanf("\n%c", &reply);
}
while(reply == 'y' || reply == 'Y');

return 0;
}



int get_gross_cost(minutes)

{
float gross_cost;
float regular_rate=0.40;

gross_cost=minutes*regular_rate;

return gross_cost;
}


int get_net_cost(start_time, minutes)

{

float regular_rate;
float net_cost;
int tax;

if (1800<start_time || start_time<800)

{
net_cost=(minutes*regular_rate/2);
tax=(net_cost*.04);
}

else
{
float net_cost=minutes;
}

return net_cost;
}

Just because variables have the same name in functions and in main doesn't mean they are the same variables.

Originally Posted by tabstop

Just because variables have the same name in functions and in main doesn't mean they are the same variables.

Are you talking about gross_cost and net_cost? I'm missing something vital here, and it seems to be whats wrong with most of my programs. Something I'm not grasping.

Originally Posted by Rockiroad278

Are you talking about gross_cost and net_cost? I'm missing something vital here, and it seems to be whats wrong with most of my programs. Something I'm not grasping.

Yes. Every function gets its own "scope", so that variables declared in one function are separate from every other function (and since main is a function, that's included too). So gross_cost in main and gross_cost in get_gross_cost aren't the same thing.

Illustrative example:

Code:

int add(int a, int b) {
    int c;
    c = a+b;
    return c;
}

int main() {
    int a = 2, b = 3, c = 4, d = 5;
    add(a,d);
    return 0;
}

The add function call will return 7, and c will still be 4, since the c in add is not the same as the c in main. The variable b in main is never used at all. If you want to use the value of 7 in main, you have to assign it to a variable (perhaps with c=add(a,d)).

Code:

#include <stdio.h>

float get_gross_cost(int);
float get_net_cost(int, int);

int main() 
{
    //Declarations
    float discount_rate, regular_rate, tax, net_cost, gross_cost;
    int minutes, start_time;
    char reply;
    
    //Explanation
    printf("This program is designed to calculate how much a long distance call between it's");
    printf("peak hours");	
    
    do
    {
        //User input
        printf("\n\nPlease enter what time you would like a call to start (0001-2400): ");
        scanf("&#37;i", &start_time);
        
        printf("\nPlease enter the duration of the call in minutes: ");
        scanf("%i", &minutes);
        
        //Functions
        gross_cost = get_gross_cost(minutes);
        
        net_cost = get_net_cost(minutes, start_time);
        
        printf("The gross cost of your call is %f", gross_cost);
        printf("\nThe net cost of your call is %f", net_cost);
        
        printf("\n\n\nWould you like to try again? <y/n>");
        scanf("\n%c", &reply);
    }
    while(reply == 'y' || reply == 'Y');
    
    return 0;
}

float get_gross_cost(int minutes)
{
    float gross_cost;
    float regular_rate=0.40;
    
    gross_cost=minutes*regular_rate;
    
    return gross_cost;
}

int get_net_cost(int start_time,int  minutes)
{

    float regular_rate;
    float net_cost;
    int tax;
    
    if (1800<start_time || start_time<800)
    {
        net_cost=(minutes*regular_rate/2);
        tax=(net_cost*.04);
    }
    else
    {
        float net_cost=minutes;
    }
    
    return net_cost;
}

This is how the indented code looks like, u should start indenting you code, so that u will get more help. And now have look at the changes which has been node on your code.

ssharish