Help generating random characters in a string

I have been trying to get my code to do the following:
Fill the first 10 indexes in string 1 & 2 with random characters
Fill the first 20 indexes with random characters in string 3

print all 3 strings out

concatenate the 2nd onto the first string (then print it out)
and a couple of other things which I have already figured out, but generating random characters has been really giving me a hard time...

I'm not exactly sure how to fill a string with random characters.

I can generate random strings, but I don't think that is really the same?

Here is what my code looks like now:

Code:

---

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


int main()
{
        char str[100] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
        char str2[100] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
        char str3[100] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};


        float x = strcmp(str, str3);
        float abs = fabs(x);
        int random = rand() %26;
        char randomLetter = 'a' + random;
        int i;


        srand(time(NULL));


        for(i = 0, i < 10 ; i++;);
        {
        int random = rand();
        }


        printf("Str1: %s\n", str);
        printf("Str2: %s\n", str2);
        printf("Str3: %s\n", str3);


        strcat(str, str2);
        printf("New Str1: %s\n", str);


        printf("Distance: %f\n", x);
        printf("Abs Distance: %f\n", abs);
        printf("Sqrt Distance: %f\n", sqrt(abs));




        return 0;
}

---

Code:

---

#include <stdio.h>
#include <math.h>

int array_gen(char *, int);

int array_gen(char *buffer, int length) {

    int i = length - 1;
    int r = 0;

    buffer[i] = '\0';

    while (0 != i) {
        i = i - 1;
        r = rand() % 26;
        buffer[i] = 'a' + r;

    }

    return 0;
}

int main(int argc, const char *argv[]) {

    char buffer[100];

    array_gen(buffer, 100);
    printf("%s\n", buffer);

    return 0;
}

---

Quote:

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I can generate random strings, but I don't think that is really the same?

---

It is impossible to generate a random number, because nothing is random.

"Spooky" quantum mechanics is quackery.

This is not random and probably won't compile.

Quote:

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Originally Posted by kodax

Code:

---

#include <stdio.h>
#include <math.h>

int array_gen(char *, int);

int array_gen(char *buffer, int length) {

    int i = length - 1;
    int r = 0;

    buffer[i] = '\0';

    while (0 != i) {
        i = i - 1;
        r = rand() % 26;
        buffer[i] = 'a' + r;

    }

    return 0;
}

int main(int argc, const char *argv[]) {

    char buffer[100];

    array_gen(buffer, 100);
    printf("%s\n", buffer);

    return 0;
}

---

---

Code:

---

#include <stdlib.h>

---

Quote:

---

This is not random

---

Because nothing is random.

Quote:

---

Originally Posted by kodax

Because nothing is random.

---

Because your code is wrong... Run it 3 times and all 3 you'll get the same result.

kodax:

You need to read the manpage for rand before attempting to use it! Ditto for other functions as well!

Code:

---

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

int array_gen(char *, int);

int array_gen(char *buffer, int length) {

    int i = length - 1;
    int r = 0;

    buffer[i] = '\0';

    while (0 != i) {
        i = i - 1;
        r = rand() % 26;
        buffer[i] = 'a' + r;

    }

    return 0;
}

int main(void) {

   srand(time(NULL));

    char buffer[100];

    array_gen(buffer, 100);
    printf("%s\n", buffer);

    return 0;
}

---

rstanley,

A question not related to the topic, but I found this interesting: How did you highlited (in red) pieces of this code using code block?

In the Quick Reply field, the "A" at the top of the box sets the font color:
Attachment 16514

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