CareerCup

#include <iostream>
using namespace std;

void Print(char* c, int n) {
  int cur = 0;
  while (cur < n) {
    int end = cur;
    while (end+1 < n && c[end+1] != '_')
      end++;

    for (int i=end; i>=cur; i--)
      printf("%c", c[i]);
    printf("."); // optional
    
    cur = end + 1;
    while (cur < n && c[cur] == '_')
      cur++;
  }
}

int main(){
  char *c = "abc__def___gh_xyz";
  Print(c, strlen(c));
  
  system("pause");
  return 0;
}

bool reverseWords( char str[] ){
char *buffer;
int tokenReadPos, wordReadPos, wordEnd, writePos = 0;

/* Position of the last character is length - 1 */
tokenReadPos = strlen(str) - 1;

buffer = (char *) malloc(tokenReadPos + 2);
if( !buffer )
return false; /* reverseWords failed */

while( tokenReadPos >= 0 ){

if( str[tokenReadPos] == ' ' ){ /* Non-word characters */
/* Write character */
buffer[writePos++] = str[tokenReadPos--];

} else { /* Word characters */
/* Store position of end of word */
wordEnd = tokenReadPos;

/* Scan to next non-word character */
while( tokenReadPos >= 0 && str[tokenReadPos] != ' ' )
tokenReadPos--;

/* tokenReadPos went past the start of the word */
wordReadPos = tokenReadPos + 1;

/* Copy the characters of the word */
while( wordReadPos <= wordEnd ){
buffer[writePos++] = str[wordReadPos++];
}
}
}
/* null terminate buffer and copy over str */
buffer[writePos] = '\0';
strcpy(str, buffer);

free(buffer);

return true; /* ReverseWords successful */
}

//Output: final string : abc__def_987654321_xyz_123abc_hi

#include <iostream>
#include <string.h>
using namespace std;
//!function to reverse string from strt to end
void reverseStr(string &s, int strt, int end) {
	while(strt<end){
		s[strt] = s[strt]+s[end];
		s[end] = s[strt]-s[end];
		s[strt] = s[strt]-s[end];
		++strt;--end;
	}
}
void reverseBuckets(string &str){
	int start=0,end=0,tmp=0,sz = str.size();
	size_t pos;
	while(end<sz){
		pos = str.find_first_of("_",start);
		if(pos>0)
		if(pos>=sz && end<sz)
			end = sz;
		else
			end = pos;
		reverseStr(str,start,end-1);
		if(end>=sz)
			break;
		pos = str.find_first_not_of("_",end);
		if(pos>0){
			end = pos;
			start=end;
		}++end;
	}
}
int main(){
	string s = "cba__fed_123456789_zyx_cba321_ih";
	reverseBuckets(s);
	cout<<"final string : "<<s<<endl;
	return 0;
}

If we're allowed extra space, we can keep reading the string (and pushing each character into a stack) until we encounter a space.. at this point, we replace the characters in the address pointed by a pointer ptr(which initially points to the beginning of the string) by popping characters off the stack. we continue this process until the original string is exhausted.

#include <cstdlib>
#include <iostream>

using namespace std;


int main(int argc, char *argv[])
{
char temp;
char arr[]= "xyz_pqr_abc";
int i=0,j=0;
while(j<11)
{
// cout << i << endl;
i=j;
cout << "i= " << i << endl;
while(arr[j]!='_' && j < 11)
{
// cout << j << endl;
j++;
cout << "j =" << j << endl;
}
j=j-1;
int k;
for(k=i;k<=(j+i)/2;k++)
{
printf("%d ",k);
temp = arr[k];
arr[k] = arr[j-k+i];
arr[j-k+i]=temp;
}
cout << endl;
j=j+2;
}
cout << arr << endl;
system("PAUSE");
return 0;
}

Here is an Iterative version:

...
	char szText[]="xyz___pqr___abc";
	cout << "Source    text: " << szText << endl;
	size_t iLen = strlen( szText );
	size_t iPos = 0;
	char *pszText = szText;
	while( iPos < iLen )
	{
		if( *pszText++ != '_' )
			iPos++;
		else
		{
			strcpy( &szText[iPos], pszText );
			pszText = &szText[iPos];
			iLen--;
		}
	}
	iLen = strlen( szText );
	char t;
	for( size_t i = 0; i < iLen; I += 3 )
	{
		t = szText[i];
		szText[i] = szText[i+2];
		szText[i+2] = t;
	}
	cout << "Corrected text: " << szText << endl;
...

Output:
Source text: xyz___pqr___abc
Corrected text: zyxrqpcba