C functions shuffle, read_vector, display_vector

Question

How can i use read_vector and display_vector in C? I have to shuffle array and then use this functions. void shuffle(int tab[], int size). I don't know if read_vector and display_vector is good. Any help will be good. (It have to be max 100 numebrs)

#include<stdio.h>

void shuffle(int tab[], int size);
int read_vector(int vec[], int size, int stop_value);
void display_vector(const int vec[], int size);

int main()
{
int i; 
int tab[101], a;

printf("Podaj pierwszy wektor: ");
for(i=0; i<100; i++)
{
a = scanf("%d", &tab[i]);
if(a<1)
{
    printf("Incorrect input");
    return 1;
}
if(tab[0]==0)
{
    printf("Not enough data available");
    return 2;
}
if(tab[i]==0)
{
    break;
}
}

shuffle(tab[i], i);

for(i=0; i<100; i++)
{
    printf("%d", tab[i]);
}
return 0;
}

void shuffle(int tab[], int size)
{
int i, j=0, x=0;

for(i=size; i>0; i--)
{
    j = rand() % size+1;
    x = tab[i];
    tab[i]=tab[j];
    tab[j]=x;
    x=0;
}

}

Answer 1

the following proposed code:

1. cleanly compiles
2. incorporates the comments to the question
3. performs the desired functionality
4. properly checks for errors
5. eliminated the 'magic' numbers 100 and 101
6. since the OPs code does not have separate functions for read_vector() nor display_vector() I did not implement them separately, However, they should be trivial to implement

And now the proposed code:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void shuffle(int tab[], int size);
//int read_vector(int vec[], int size, int stop_value);
//void display_vector(const int vec[], int size);

#define MAX_VECTOR_LENGTH 100

int main( void )
{
    int i; 
    int tab[ MAX_VECTOR_LENGTH ];

    srand( (unsigned)time( NULL ) );

    printf("Podaj pierwszy wektor:\n ");
    for(i=0; i<MAX_VECTOR_LENGTH; i++)
    {
        printf( "%s", "enter vector entry or 0 to indicate done " );
        if( scanf("%d", &tab[i]) != 1)
        {
            fprintf( stderr, "scanf failed\n");
            exit( EXIT_FAILURE );
        }

        // implied else, scanf successful

        if(tab[i]==0)
        {
            break;
        }
    }

    shuffle(tab, i-1);

    for(int j = 0; j < i; j++)
    {
        printf("%d  ", tab[j]);
    }
    return 0;
}


void shuffle(int tab[], int size)
{
    int i;
    int j;
    int x;

    for(i=size; i>0; i--)
    {
        j = rand() % size;
        x = tab[i];
        tab[i]=tab[j];
        tab[j]=x;
    }
}

A typical run of the program results in:

Podaj pierwszy wektor: 
enter vector entry or 0 to indicate done 1
enter vector entry or 0 to indicate done 2
enter vector entry or 0 to indicate done 3
enter vector entry or 0 to indicate done 4
enter vector entry or 0 to indicate done 5
enter vector entry or 0 to indicate done 6
enter vector entry or 0 to indicate done 7
enter vector entry or 0 to indicate done 0
1  6  5  3  4  7  2