array operations in c using pointers

Question

In the program below, inside the main function, while entering elements in an array it runs one more time and also the insertion function is inserting random values.
I think I am doing a mistake in the insertion function. Here I want to first shift the elements and then I want to insert when it found an element smaller than that I want to insert.

#include<stdio.h>
#include<stdlib.h>
struct Array
{
    int *A;
    int length;
    int size;
} p;
        
void Display(struct Array p)
{
    int i;
    for(i=0;i<p.length;i++)
    {
        printf(" %d ",p.A[i]);
    }
}
       
// I think I am doing a mistake in the insertion function below. Here I want to first shift the elements and then I want to insert when it found an element smaller than that I want to insert.

void inserting(struct Array *p,int x)
{
    int i=p->length-1;
    if(p->length=p->size)
    {
        return;
    }
    while(i>=0 && p->A[i]>x)
    {
        p->A[i+1]=p->A[i];
        i--;
    }
    p->A[i+1]=x;
    p->length++;    
}
    
    
int main()
{
    int i,ch,index,el,choice=1,c;
    printf("Enter size of array\n");
    scanf("%d",&p.size);
    p.A=(int *)malloc(p.size * sizeof(int));
    printf("Enter length of Array\n");
    scanf("%d",&p.length);
    printf("ENTER elements in an array\n");
    for(i=0;i<p.length;i++)
    {
        scanf("%d\n",&p.A[i]);
    }
    // The above loop takes input one more time than expected.
    inserting(&p,20);
    Display(p);
    return 0;
}

For the first problem: `scanf("%d\n",&p.A[i]);` -> `scanf("%d",&p.A[i]);`. See: [What is the effect of trailing white space in a scanf() format string?](https://stackoverflow.com/questions/19499060/what-is-the-effect-of-trailing-white-space-in-a-scanf-format-string) — kaylum, Jul 03 '21 at 05:23
Next problem: `if(p->length=p->size)` --> `if(p->length==p->size)` — kaylum, Jul 03 '21 at 05:25
If you are using `gcc` or `clang`, you should pretty much always compile with the flags `-Wall` and `-Wextra`. They enable a lot of warnings, which should help you catch a lot of errors early. — Dada, Jul 03 '21 at 12:28

score 2 · Accepted Answer · answered Jul 03 '21 at 05:25

2

        if(p->length=p->size)

Assignment in a conditional, a decent compiler I think would warn for this.

answered Jul 03 '21 at 05:25

Richard Rowell

318
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array operations in c using pointers

1 Answers1