help me! return a string

**nawzays** · 08-16-2011

Code:

#include <stdio.h>
#include <conio.h>
#include <string.h>
int menu();
char get_item(int choice);
float get_price(int choice);
float get_pay(int qty,float price);
void display(char , char , float, int, float);

int main()
{
    char name;
    int item,choice,qty;
    float price,payment;
    menu();
    display(name,item ,price,qty,payment);
    item=get_item(choice);
    price=get_price(choice);
    payment=get_pay(qty,price);
    getche(); 
}


int menu()
{
  char name[20];
  int item,choice,qty;
  float payment,price;

        printf("\n----------------------------------------------------");
        printf("\n-           WELCOME TO MYCAR ACCESORIES            -");
        printf("\n----------------------------------------------------");
        printf("\n1.  Pioneer MP3 Player    [ $ 350.00 ]");
        printf("\n2.  MOMO Sports Steering  [ $ 770.00 ]");
        printf("\n3.  MOMO Gear Knob        [ $ 150.00 ]");     
        printf("\nEnter name      : ");
        gets(name);
        printf("Enter choice    : ");
        scanf("%d", &choice);
        printf("Enter quantity  : ");
        scanf("%d", &qty);
}

char get_item(int choice)
{
     int item[30];
     switch (choice) 
    {
        case 1: strcpy(item" Pioneer MP3 Player");
                   break;
        case 2: strcpy(item" MOMO Sports Steering");
                   break;
        case 3: strcpy(item" MOMO Gear Knob");
                   break;
	default:
                  strcpy(item"Error! Try again please\n");
     }return item;
}

float get_price(int choice)
{
    	float price;

	switch (choice) 
    {
        case 1: price = 350.00;
                   break;
        case 2: price = 770.00;
                   break;
        case 3: price = 150.00;
                   break;
	    default:price=0;
     }
  return price;

}
float get_pay(int qty,float price)
{
	float payment;
	
	payment = qty * price;

	return payment;
}

	

void display(char name,char item , float price, int qty, float payment)
{
	printf("\nName                : %s", name);
	printf("\nItem                : %s", item);
	printf("\nPrice               : RM %.2f", price);
	printf("\nQuantity            : %d", qty);
	printf("\nPayment             : RM %.2f\n\n", payment);
}

i cant get it to run..help please..i'm a newbie here

**tabstop** · 08-16-2011

As long as you've got conio.h and gets in your program, no one here will be able to compile it; so if you want help with the errors you'll have to tell us what the errors are.

**nawzays** · 08-16-2011

Code:

char get_item(int choice)
{
     int item[30];
     switch (choice) 
    {
        case 1: strcpy(item" Pioneer MP3 Player");
                   break;
        case 2: strcpy(item" MOMO Sports Steering");
                   break;
        case 3: strcpy(item" MOMO Gear Knob");
                   break;
	default:
                  strcpy(item"Error! Try again please\n");
     }return item;
}

i'm stuck here...i cant return it...

**subhash.rao** · 08-16-2011

Originally Posted by nawzays

Code:

#include <stdio.h>
#include <conio.h>
#include <string.h>
int menu();
char get_item(int choice);
float get_price(int choice);
float get_pay(int qty,float price);
void display(char , char , float, int, float);

int main()
{
    char name;
    int item,choice,qty;
    float price,payment;
    menu();
    display(name,item ,price,qty,payment);//values in any function wont affect these variables
    item=get_item(choice);
    price=get_price(choice);
    payment=get_pay(qty,price);
    getche(); 
//return 0; missing here
}


int menu()
{
  char name[20];
  int item,choice,qty;
  float payment,price;

        printf("\n----------------------------------------------------");
        printf("\n-           WELCOME TO MYCAR ACCESORIES            -");
        printf("\n----------------------------------------------------");
        printf("\n1.  Pioneer MP3 Player    [ $ 350.00 ]");
        printf("\n2.  MOMO Sports Steering  [ $ 770.00 ]");
        printf("\n3.  MOMO Gear Knob        [ $ 150.00 ]");     
        printf("\nEnter name      : ");
        gets(name);
        printf("Enter choice    : ");
        scanf("%d", &choice);
        printf("Enter quantity  : ");
        scanf("%d", &qty);
}

char get_item(int choice)
{
     int item[30];
     switch (choice) 
    {
        case 1: strcpy(item," Pioneer MP3 Player");
                   break;
        case 2: strcpy(item," MOMO Sports Steering");
                   break;
        case 3: strcpy(item," MOMO Gear Knob");
                   break;
	default:
                  strcpy(item,"Error! Try again please\n");
     }return item;
}

float get_price(int choice)
{
    	float price;

	switch (choice) 
    {
        case 1: price = 350.00;
                   break;
        case 2: price = 770.00;
                   break;
        case 3: price = 150.00;
                   break;
	    default:price=0;
     }
  return price;

}
float get_pay(int qty,float price)
{
	float payment;
	
	payment = qty * price;

	return payment;
}

	

void display(char name,char item , float price, int qty, float payment)
{
	printf("\nName                : %s", name);
	printf("\nItem                : %s", item);
	printf("\nPrice               : RM %.2f", price);
	printf("\nQuantity            : %d", qty);
	printf("\nPayment             : RM %.2f\n\n", payment);
}

i cant get it to run..help please..i'm a newbie here

there are too many mistakes in the code...all the variables are local to the functions which do not affect the local variables of main from which u are trying to get price,item,etc...even display wont work.....the item is declared and used as atleast 3 different datatypes...

**nawzays** · 08-16-2011

Code:

#include <stdio.h>
#include <conio.h>
#include <string.h>
int menu();
char get_item(int choice);
float get_price(int choice);
float get_pay(int qty,float price);
void display(char , char , float, int, float);

int main()
{
    char name,item;
    int choice,qty;
    float price,payment;
    
 	menu();
    display(name,item ,price,qty,payment);

    getche(); 
    return 0;
}

int menu()
{
  char  item,name[20];
  int choice,qty;
  float payment,price;

        printf("\n----------------------------------------------------");
        printf("\n-           WELCOME TO MYCAR ACCESORIES            -");
        printf("\n----------------------------------------------------");
        printf("\n1.  Pioneer MP3 Player    [ $ 350.00 ]");
        printf("\n2.  MOMO Sports Steering  [ $ 770.00 ]");
        printf("\n3.  MOMO Gear Knob        [ $ 150.00 ]");     
        printf("\nEnter name      : ");
        gets(name);
        printf("Enter choice    : ");
        scanf("%d", &choice);
        printf("Enter quantity  : ");
        scanf("%d", &qty);
        
         item=get_item(choice);
         price=get_price(choice);
         payment=get_pay(qty,price);
         
}
char get_item(int choice)
{
	char item[30];
	
	switch (choice) 
    {
        case 1: strcpy(item, " Pioneer MP3 Player");
          break;
        case 2: strcpy(item, " MOMO Sports Steering");
          break;
        case 3: strcpy(item, " MOMO Gear Knob");
          break;
	    default:
          strcpy(item,"Error! Try again please");break;
     }
     return item;
}

float get_price(int choice)
{
    
 	float price;

	switch (choice) 
    {
        case 1: price = 350.00;
          break;
        case 2: price = 770.00;
          break;
        case 3: price = 150.00;
          break;
	    default:
          price=0;
     }
  return price;

}
float get_pay(int qty,float price)
{
	float payment;
	
	payment = qty * price;

	return payment;
}

	

void display(char name,char item, float price, int qty, float payment)
{
	printf("\nName                : %s", name);
	printf("\nItem                : %s", item);
	printf("\nPrice               : RM %.2f", price);
	printf("\nQuantity            : %d", qty);
	printf("\nPayment             : RM %.2f\n\n", payment);
}

i repaired it but still wont work.. :'(

**nawzays** · 08-16-2011

it say in function char get_item
invalid conversion from 'char*' to 'char'

**rogster001** · 08-16-2011

now your code seems a little more formatted you might get some other replies ;->

You forgot ',' in the strcpy for one thing
perhaps have a look at the following,
Also perhaps make an enum list to label your switch cases

Code:

enum ITEM_LIST 
{
    PIONEER_MP3,
    MOMO_SPT_STEERING,
    MOMO_GEARKNOB,
};


void GetItem(int choice, char item[30]);

int main()
{
    char item[30];  //fixed size remember....
    int choice = 0;
    
    //get user input for choice (checking for invalid input of course... ;-> )
    //....
    GetItem(choice, item);
    
    //output your results....whatever
    
    return 0;
}

void GetItem(int choice, char item[30])
{
    
    switch (choice) 
    {
        case PIONEER_MP3: 
            strcpy(item, "Pioneer MP3Player");
        break;
        case MOMO_SPT_STEERING: 
            strcpy(item, "MOMO Sports Steering");
        break;
        case MOMO_GEARKNOB: 
            strcpy(item, "MOMO Gear Knob");
        break;
        
        default:
        strcpy(item, "Error! Try again please\n");
    }
     
}

??code in tags seems to be losing formatting then not, probably this browser...

**manasij7479** · 08-16-2011

Originally Posted by nawzays

it say in function char get_item
invalid conversion from 'char*' to 'char'

item is a char array and you are returning a char. What you can do is, pass a char array into the function and its size. Then input the value directly into it, possibly checking that it doesn't exceed the size.
Then correct the other problems in the code, if there.

[Edit: Couldn't we get a mutex for the last reply being posted ?!]

Originally Posted by rogster001

??code in tags seems to be losing formatting then not, probably this browser...

Happens to me too. More often than not when using a slow connection and when the Edit icons in the Advanced page doesn't appear.

**nawzays** · 08-16-2011

can someone modified my answer?

the question ask me to call menu,get_item,get_price,payment,and display....isk3..i quite blur in c programming...sorry guys..

**~~CommonTater~~** · 08-16-2011

I won't fix it for you but here's one reason it's not working....

Code:

char get_item(int choice)
{
	char item[30];
	
	switch (choice) 
    {
        case 1: strcpy(item, " Pioneer MP3 Player");
          break;
        case 2: strcpy(item, " MOMO Sports Steering");
          break;
        case 3: strcpy(item, " MOMO Gear Knob");
          break;
	    default:
          strcpy(item,"Error! Try again please");break;
     }
     return item;
}

Ok inside this function you declare a char array item[]. This exists locally to your function and is destroyed when the function exits. But... you are attempting to return a pointer to it at the end of the function. By the time your next function tries to read the string, it's long gone.

This is about "scope" (look it up in your text books) basically anything after the opening brace only lasts until the matching closing brace...

Code:

// variable not available

{ 
   int variable;
   // here variable is useable
}
// variable not available

Now... take a good look at your code with this in mind.

**tabstop** · 08-16-2011

And to add to what Tater just said: when you return something from a function, a copy of that thing is made and that copy goes back to whoever called the function. For a simple data type, that's all that is needed. For arrays, however, the array name by itself refers to the location of the first element (in memory), and when you return that array a copy of that address (not the data actually in the array) is made and returned. And then, when that array goes out of scope (as above), that address is no longer useful.

**~~CommonTater~~** · 08-16-2011

Here's a small sample program... type it up and compile it.... Try it with and without the static keyword...
This is why you should never try to return an array from a function. And yes "char string[20]" is an array.

Code:

#include <stdio.h>

int* MyFunction(int a, int b, int c)
  {  static int array[3];
     array[0] = a;
     array[1] = b;
     array[2] = c;
     return array;  } // return a pointer.


int main (void)
  { int *a1, *a2;  // int pointers

    printf("calling a1 = MyFunction(10,20,30);\t");
    a1 = MyFunction(10,20,30);
    printf("a1 has %d %d %d\n",a1[0],a1[1],a1[2]);

    printf("calling a2 = MyFunction(100,200,300);\t");
    a2 = MyFunction(100,200,300);
    printf("a2 has %d %d %d\n",a2[0],a2[1],a2[2]);

    printf("\nLooks good, except...\t"); 
    printf("a1 now has %d %d %d\n",a1[0],a1[1],a1[2]);

    getchar();
    return 0; }

**nawzays** · 08-16-2011

thank to all of guys....tahnk you so much.u guys help alot

**valthyx** · 08-16-2011

Code:

char get_item(int choice)
{
	char item[30];
	
	switch (choice) 
    {
        case 1: strcpy(item, " Pioneer MP3 Player");
          break;
        case 2: strcpy(item, " MOMO Sports Steering");
          break;
        case 3: strcpy(item, " MOMO Gear Knob");
          break;
	    default:
          strcpy(item,"Error! Try again please");break;
     }
     return item;
}

To return a string, do this:

Code:

char* get_item(int choice)
{
	char item[30];
	
	switch (choice) 
    {
        case 1: strcpy(item, " Pioneer MP3 Player");
          break;
        case 2: strcpy(item, " MOMO Sports Steering");
          break;
        case 3: strcpy(item, " MOMO Gear Knob");
          break;
	    default:
          strcpy(item,"Error! Try again please");break;
     }
     return item;
}

**AndrewHunter** · 08-16-2011

Did you miss all the other posts about this topic!?! You cannot, I repeat, cannot return a pointer to a local variable, this includes arrays. The variable goes out of scope when the funtion ends, hence the pointer (like your solution) is useless.

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