Copying function problem

**ronrardin** · 03-03-2010

Hi all,

I am writing a function to copy one struct(called instruction) to another

Code:

void copy_struct(instruction src,instruction dest)
{
dest.inst_addr = src.inst_addr;
dest.inst_func = src.inst_func ;
dest.inst_destreg = src.inst_destreg;
dest.src1 = src.src1;
dest.src2 = src.src2;
}
copy_struct(instruction1,instruction2)

But when I call copy_struct(instruction1,instruction2) it is not getting copied. Do I have to declare it as pointers or something in the fuction? Please help me fix the problem.

**vivekraj** · 03-03-2010

Yeah ronrardin,you're correct.You need to pass the arguments to copy_function as pointers.Then only the changes done will be get affected after you return from the function.Else,the structure values will be copied and the values will be lost after the function scope ends.

**ungalnanban** · 03-03-2010

no need to assign all the values. you need to send two pointers to the function that will copy the structure.

Code:

void copy_struct(instruction *src, instruction *dest)
{
 *dest=*src;
}

See the Example:

Code:

#include<stdio.h>

typedef struct
{
        int inst_addr;
}instruction;

void copy_struct(instruction *src,instruction *dest)
{
        *src=*dest;
}


int main()
{
        int addr = 1000;
        instruction check1;
        instruction check2;

        check1.inst_addr = 10;
        check2.inst_addr = 50;
        printf("One: %d\n",check1.inst_addr);
        printf("Two: %d\n",check2.inst_addr);
        copy_struct(&check1,&check2);
        printf("One: %d\n",check1.inst_addr);
        printf("Two: %d\n",check2.inst_addr);
}

Output:
One: 10
Two: 50
One: 50
Two: 50

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