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POHow to generate a new random number and transpose the matrix?
 

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  1. POHow to generate a new random number and transpose the matrix?
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    <p>Thanks for all helped me before. But I still have some questions about the program. How to generate a new random number while the new random number is equal to the previous random number? Also how to transpose the matrix? </p> <pre><code>#include "stdafx.h" #include "stdlib.h" #include "time.h" int _tmain(int argc, _TCHAR* argv[]) { int num2 = 0; int num=0, i, j; int mtx[9][9] = {0}; while (num &lt; 3 || num &gt; 9) { printf("Enter an integer (3-9): "); scanf("%d", &amp;num); } do { srand(time(NULL)); switch (num) { case 3: num2 = rand() % 8; break; case 4: num2 = rand() % 15; break; case 5: num2 = rand() % 24; break; case 6: num2 = rand() % 35; break; case 7: num2 = rand() % 48; break; case 8: num2 = rand() % 63; break; case 9: num2 = rand() % 80; break; } for (i=0; i &lt; num; ++i) for (j=0; j &lt; num; ++j) mtx[i][j] = num2; } while ( num2 == num2); for (i=0; i &lt; num; ++i) { for (j=0; j &lt; num; ++j) printf("%i ", mtx[i][j]); printf("\n"); } return 0; } </code></pre> <hr> <p>Update:</p> <pre><code>#include "stdafx.h" #include "stdlib.h" #include "time.h" int _tmain(int argc, _TCHAR* argv[]) { int prevNum2 = 0; int num2 = 0; int num = 0, i, j; // Added initializers and loop counters int mtx[9][9] = {0}; // Reserve enough space for the worst-case scenario while (num &lt; 3 || num &gt; 9) { // Added input validation loop printf("Enter an integer (3-9): "); scanf("%d", &amp;num); } srand(time(NULL)); do{ prevNum2 =num2; switch (num) { case 3: num2 = rand() % 8; break; case 4: num2 = rand() % 15; break; case 5: num2 = rand() % 24; break; case 6: num2 = rand() % 35; break; case 7: num2 = rand() % 48; break; case 8: num2 = rand() % 63; break; case 9: num2 = rand() % 80; break; } // Loop through the matrix elements we want, filling each with a random number for (i=0; i &lt; num; ++i) for (j=0; j &lt; num; ++j) mtx[i][j] = num2; } while (num2 == prevNum2); /* Do something with the matrix here (display it, etc) */ for (i=0; i &lt; num; ++i) { for (j=0; j &lt; num; ++j) printf("%i ", mtx[i][j]); printf("\n"); } return 0; } </code></pre>
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    1. USProgramme Newbie
    1. USProgramme Newbie
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    1. COTake the srand() out of the loop. And read some of the many, many questions here on random number generation.
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    2. COThis is incredibly ineffecient way of doing what you're doing. You want to assign all the numbers from `0` to `n-1` (`n = num*num`) to `mtx`. Generating random numbers in the range `0` to `n-1`, and then checking if it's not yet generated becomes really slow as your pool of available numbers becomes smaller. For example, when you've generated 80 such numbers, you know what the 81st number should be, but doing it by your algorithm will likely take a long time before you find the number you want. What you're looking for is a way to shuffle the numbers between `0` and `num*num-1`.
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      1. POHow to generate a new random number and transpose the matrix?
      1. USAlok Singhal
 

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