how to write a function that would return a string in c

Question

How to return a string from the function:

char * temp;

int main()
{
    temp = malloc(129);

    double g_symbol_b_amount = 8536.700000;
    printf("\n value: %s\t ", format_double_trans_amount(double g_symbol_b_amount));
}

char *format_double_trans_amount(double amount)
{
    char amount_array_n1[25]; 
    strcpy(amount_array_n, "");
    sprintf(amount_array_n, "%1f", amount);
    temp = amount_array_n;
    return temp;
}

Here I got the value: 0.000000
I need the orginal value, please help me on this?

what is amount_array_n? Does this compile for you? Can you show the exact output generated? — Amir Rachum
– Amir Rachum, Commented Apr 30, 2011 at 15:23

CRM · Accepted Answer · 2011-04-30 16:03:14Z

1

I've tested the code below and it behaves correctly. Can you please confirm.

#include "stdio.h"
#include "stdlib.h"

char * temp;

char *format_double_trans_amount(double amount)
{
    sprintf(temp,"%1f",amount);
    return temp;
}

int main()
{
    double g_symbol_b_amount = 8536.700000;
    temp = (char*) malloc( sizeof(char) * 129);
    printf("\n value: %s\n", format_double_trans_amount(g_symbol_b_amount));
    free(temp);
}

edited Apr 30, 2011 at 16:03

answered Apr 30, 2011 at 15:33

CRM

4,6554 gold badges29 silver badges35 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

CRM Over a year ago

@jcrshankar What environment are you using for compiling/testing the example? I've tested with Linux and gcc, and the value is correctly printed!

CRM Over a year ago

@jcrshankar Cool! Do you know what the problem was?

Jonathan Wood · Accepted Answer · 2011-04-30 15:28:36Z

1

Your printf() format string should have %s instead of %f because the value being passed (the value returned from format_double_trans_amount) is a char * and not a double.

I think you should also change your format_double_trans_amount() function to:

char *format_double_trans_amount(double amount)
{      
    sprintf(temp,"%1f",amount);   
    return temp;  
}

edited Apr 30, 2011 at 15:28

answered Apr 30, 2011 at 15:23

Jonathan Wood

68.1k86 gold badges309 silver badges542 bronze badges

5 Comments

Brian Roach Over a year ago

Which is all well and good, except amount_array_n in format_double_trans_amount doesn't exist. I suspect he doesn't understand that whole stack vs. heap thing either ;)

Jonathan Wood Over a year ago

@Brian: According to the OP, his code is running and so it must exist, whether we know where or not. However, I've already modified my answer to point out it is not needed.

Brian Roach Over a year ago

Neither is returning anything from format_double_trans_amount since temp is global. Ignoring the first problem you pointed out which is of course important, his question is asking how you return a "string" from a function.

Jonathan Wood Over a year ago

@Brian: Your objection appear to be a moving target here :-) but just because a variable is global does not mean it cannot be returned from a function. Clearly, the structure of the code is lacking. But I've corrected the OP's error, and I've made a suggested improvement. I think that's enough to start with.

Jonathan Wood Over a year ago

@jcrshankar: "nowt working" is not enough information to tell what problems you might still be having.

Collectives™ on Stack Overflow

how to write a function that would return a string in c

2 Answers 2

2 Comments

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related