CODEWITHSUNDEEP
carraysstringrandomchar
xxFlashxx
xxFlashxx

Reputation: 271

Inputing string and printing them in random order

I'm having a little trouble getting my words to print out in random order. The 8 words that I insert will need to be printed out in random order. Right now I'm only able to generate a few of them in random order because it overwrites the previous space if the same number is generated twice. How can I eliminate this issue? 

    #include <stdio.h>
    #include <stdlib.h>
    #include <time.h>
    #include <string.h>
    #include <ctype.h>
    #define MAX 50

    int readLine(char string[]);

    int main(void)
    {
        int i;
        char str[8][MAX], temp[8][MAX];
        srand((unsigned)time(NULL));
        int r_num;

        printf("Enter 8 words:\n");

        for(i=0; i<8; ++i)
        {
            readLine(str[i]);
        }


        for (int i = 0; i < 8; i++)
        {
            r_num = rand()%8+1;
            strcpy(temp[r_num], str[i]);
        }

    printf("\nRandom order of words: \n");
    for(i=0; i<8; ++i)
    {
        printf("%s\n", temp[i]);
    }
    printf("\n");

    return 0;
}

int readLine(char string[])
{
    int ch;
    int i=0;
    while (isspace(ch = getchar()))
        ;
    while (ch != '\n' && ch != EOF)
    {
        if (i < MAX)
        {
            string[i++] = ch;
            ch = getchar();
        }
    }
    string[i] = '\0';
    return i;
}

Upvotes: 1

Views: 1035

Answers (3)

Akshay Patole
Akshay Patole

Reputation: 474

You need to take care that you should not copy the same data into temp array.

You can check following simple logic,

1) Find the randno r_num

2) Swap. str[r_num] and str[maxlen]

3) Decrement max len by 1

4) Repeat

for ( i = 0; i < 8; i++)
{
    // Commenting your code 
    //r_num = rand()%8+1;
    //strcpy(temp[r_num], str[i]);

    memset(temp1,0,sizeof(temp1));
    r_num = (rand()%(8-i))+1;
    if(r_num != i) // Do not swap if r_num is max
    {
        //swapping
        strcpy(temp1,str[r_num]);
        strcpy(str[r_num],str[7-i]);
        strcpy(str[7-i],temp1);
    }
}

I hope this will help you :)

Upvotes: 1

J. Piquard
J. Piquard

Reputation: 1663

Before storing a input line string[i] in a random output line temp[r_num], you have just to verify if the selected output is free.

First step, initialize the output array temp[8][MAX] from the first loop:

for(i=0; i<8; ++i)
{
    strcpy(temp[i],""); // set each output line to free (empty).
    readLine(str[i]);
}

Second step, loop on the randomize selector while the selected string is not output: The random index shall be from 0 to 7.

for (i = 0; i < 8; i++)
{
    do {
        r_num = rand()%8; // index is between 0 and 7
    } while (strlen(temp[r_num])!=0); // output shall be free/empty
    strcpy(temp[r_num], str[i]);
}

Instead of:

    for (int i = 0; i < 8; i++)
    {
        r_num = rand()%8+1; // error index start from 0
        strcpy(temp[r_num], str[i]);
    }

Upvotes: 0

MikeCAT
MikeCAT

Reputation: 75062

One of ways to shuffle data is picking from what is not selected yet.

int main(void)
{
    int i;
    char str[8][MAX];
    int order[8]; /* order list */
    srand((unsigned)time(NULL));
    int r_num;

    printf("Enter 8 words:\n");

    for(i=0; i<8; ++i)
    {
        readLine(str[i]);
    }

    /* initialize order list */
    for (i = 0; i < 8; i++)
    {
        order[i] = i;
    }
    for (i = 7; i > 0; i--) /* select from back to front */
    {
        int pos = rand() % (i + 1); /* pick one position randomly */
        /* pick selected element by swapping */
        int temp = order[pos];
        order[pos] = order[i];
        order[i] = temp;
    }

    printf("\nRandom order of words: \n");
    for(i=0; i<8; ++i)
    {
        printf("%s\n", str[order[i]]); /* print strings in the shuffled order */
    }
    printf("\n");

    return 0;
}

Upvotes: 1

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