String Processing — Write out a function that prints out all the permutations of a String. For example, abc would give you abc, acb, bac, bca, cab, cba.

void PrintPermu (char *sBegin, char* sRest) 
 { 
      int iLoop; 
      char cTmp; 
      char cFLetter[1]; 
      char *sNewBegin; 
      char *sCur; 
      int iLen; 
      static int iCount; 
      iLen = strlen(sRest); 
      if (iLen == 2) 
        { 
                 iCount++; 
                 printf("%d: %s%s\n",iCount,sBegin,sRest); 
                 iCount++; 
                 printf("%d: %s%c%c\n",iCount,sBegin,sRest[1],sRest[0]); 
                 return; 
         } 
      else if (iLen == 1) 
        { 
                iCount++; 
                printf("%d: %s%s\n", iCount, sBegin, sRest); 
                return; 
         } 
      else 
        { 
              // swap the first character of sRest with each of 
              // the remaining chars recursively call debug print 
                 sCur = (char*)malloc(iLen); 
                 sNewBegin = (char*)malloc(iLen); 
                 for (iLoop = 0; iLoop < iLen; iLoop ++) 
                      { 
                           strcpy(sCur, sRest); 
                           strcpy(sNewBegin, sBegin); 
                           cTmp = sCur[iLoop]; 
                           sCur[iLoop] = sCur[0]; 
                           sCur[0] = cTmp; 
                           sprintf(cFLetter, "%c", sCur[0]); 
                           strcat(sNewBegin, cFLetter); 
                           debugprint(sNewBegin, sCur+1); 
                      } 
           } 
 } 
            void main() 
      { 
            char s[255]; 
            char sIn[255]; 
            printf("\nEnter a string:"); 
            scanf("%s%*c",sIn); 
            memset(s,0,255); 
            PrintPermu(s, sIn); 
       }