How to fill an array by extracting a partial array

Question

I was trying to fill an array,xlow, by extracting some elements from an array called exit_2. By making the array xlow, I wanted access specific elements of it but the code gives some weird numbers.

#include <stdio.h>
int main()
{
 int exit_1[4]={3,0,7,11},exit_2[4]={90,164,232,328},xlow[2],i;
 for(i=0;i<4;++i){
    if(exit_1[i]<7){
        xlow[2]=exit_2[i];
    }
}
 printf("%d",xlow[0]);
 return 0;
}

Thank you your help

Gopi · Accepted Answer · 2015-03-30 04:17:54Z

1

xlow[2]=exit_2[i];

As you see you are initializing xlow[2]. xlow[0] is still uninitialized and using uninitialized variables lead to undefined behavior.

int j=0;
 for(i=0;i<4;++i){
    if(exit_1[i]<7){
        if(j>1)
        break;
        else
        xlow[j++]=exit_2[i];
    }
}

answered Mar 30, 2015 at 4:17

Gopi

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Loocid · Accepted Answer · 2015-03-30 04:16:03Z

0

You will get weird numbers because xlow[0] is never written to or initialized, you only ever write to xlow[2].

That means when you do printf("%d",xlow[0]);, the program will just print whatever random values are in the memory location of xlow[0].

answered Mar 30, 2015 at 4:16

Loocid

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