How do I generate random characters within a string using C?

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I was given this code to start:

C++

char s[21];

    for ( k = 0; k < 20; k++ )
        s[k] = ' ';
    s[20] = '\0';

    printf("|%s|\n", s);

I have to include the following into the code i have:
- place 5 random characters within string s
- symbol should be a lowercase character
- location/position must be within valid string

The final code should generate (without the periods, just spaces):

|...................|
|..l..gy..x...c|

the letters and spacing can be random, but must stay within the string

What I have tried:

I haven't been able to get past this:

C++

char s[21];

    for ( k = 0; k < 20; k++ )
        s[k] = ' ';
    s[20] = '\0';

    printf("|%s|\n", s);
    printf("\n");

    return 0;
}

Any help would be appreciated as I really struggle with coding. Thanks!

Posted 1-Nov-19 16:07pm

M241220

Updated 1-Nov-19 23:55pm

RickZeeland

v2

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Peter_in_2780 2-Nov-19 0:09am

Think about how you would do it with pencil and paper.
Note down those steps.
Translate them into code.
Compile and test.

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RickZeeland · Answer 1 · 2019-11-01T23:51:00

Solution 1

Hint: take a look at C library function - rand() - Tutorialspoint[^]
And: C library function - tolower() - Tutorialspoint[^]

Posted 1-Nov-19 23:51pm

RickZeeland

OriginalGriff · Answer 2 · 2019-11-01T23:55:00

Start by setting up a char array, which contains the characters you want to choose from. For "all lowercase characters" that would be:

C++

char pickFrom[] = "abcdefghijklmnopqrstuvwxyz";

Then create a random number generator using srand: C library function - rand() - Tutorialspoint[^]
You can now use rand inside a loop to "pick" random characters from the array (using the modulus operator) and set them into your output string.

Give it a try: it's isn't hard to do if you think about it!