c - 如何生成新的随机数并转置矩阵？

Question

感谢之前所有帮助过我的人。但是我对这个程序还有一些疑问。如何在新随机数等于先前随机数的情况下生成新随机数？还有如何转置矩阵？

#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 < 3 || num > 9) {  
        printf("Enter an integer (3-9): ");  
        scanf("%d", &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 < num; ++i)  
        for (j=0; j < num; ++j)  
            mtx[i][j] = num2;  
} 
while ( num2 == num2); 



    for (i=0; i < num; ++i) {  
    for (j=0; j < num; ++j)  
        printf("%i ", mtx[i][j]);  
    printf("\n");  
}  



    return 0; 
} 

---

更新:

#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 < 3 || num > 9) { // Added input validation loop 
        printf("Enter an integer (3-9): "); 
        scanf("%d", &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 < num; ++i) 
        for (j=0; j < num; ++j) 
            mtx[i][j] = num2; 
    }
    while (num2 == prevNum2);

    /* Do something with the matrix here (display it, etc) */ 

    for (i=0; i < num; ++i) { 
    for (j=0; j < num; ++j) 
        printf("%i ", mtx[i][j]); 
    printf("\n"); 
} 



    return 0;
}

Answer 1

读取的代码段

 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;
   }

可以重写为

 num2 = rand() % ((num * num) - 1);

哪个更紧凑，可以说更清晰。