Given For e.g, char input[] = "10011210582553796"; now Hexadecimal of 10011210582553796 is 2391249A8B74C4. So output unsigned char* should have value, unsigned char output[8] = {0x00,0x23,0x91,0x24,0x9A,0x8B,0x74,0xC4}; can anyone give a solution to convert given input char* to output char* with above mentioned requirement. code should run on platform for which __int64/signed long long is not supported. Thanx in advance...

It's easy enough, how far have you got and where are you stuck? We won't write your program for you (unless you're willing to pay) but we'll help you debug it.

Re: any solution to convert given char*(number) to required unsigned char*(hex of num found the solution Code: int number = 0; char numberchars[] = "12545555685986589"; int i = 0; int ans = 0; int carry = 0; char answerArray[100] = {0}; char remainderArray[100] = {0}; int remindex = 0; int ansindex = 0; int remainder = 0; while( numberchars[i] != '\0' ) { while( numberchars[i] != '\0' ) { char currentchar[2] = {0}; currentchar[0]=numberchars[i]; int num = atoi(currentchar); num += remainder; remainder = 0; if ( num < 2 ) { remainder = num; if(i>0) answerArray[ansindex++] = '0'; } else { remainder = num % 2; int answer = num / 2; char a[2] = {0}; itoa(answer,a,10); answerArray[ansindex++] = a[0]; } i++; remainder *= 10; } char a[2] = {0}; int rval = remainder / 10; itoa(remainder / 10,a,10); remainderArray[remindex++] = a[0]; int size = sizeof(answerArray); memcpy(numberchars,answerArray,sizeof(answerArray)); size = sizeof(answerArray); memset(answerArray,0,sizeof(answerArray)); ansindex = 0; remainder = 0; i=0; } char int64[8] = {0}; for(int k=0;remainderArray[k]!= '\0';k++) { int64[7-(k/8)] |= ((remainderArray[k]-'0') << (k%8)); }