#include <stdio.h>
#include <stdlib.h>
void main()
{
       FILE *pt;
       int a,b,cnum,gnum,t;
   printf("Characters of password: ");
       scanf("%d",&cnum);
       printf("How many passwords: ");
       scanf("%d",&gnum);
       pt = fopen("logs.txt","w");
       for(a=0;a<gnum;a++)
       {
      for(b=0;b<cnum;b++)
          {
                 fprintf(pt,"%c",charset(random(62)));
          }
              fprintf(pt,"\n");
       }
       printf("\nAll passwords are in \"logs.txt\"");
       printf("\nPress any key to continue ...");
   getch();
}
int charset(n)
{
       char ch;
       switch(n){
              這裡
              其實可以用ASCII的轉換
              1.你....0~9直接ch==n即可
              2.10~35轉a~z用ASCII即可
              3.同上..........
       }
       return ch;
}
C++我不太熟  
 
 只能做到這邊而已...........