// ENGR 131, Monday 3:30 Recitation (Amanda Rohn)
// Homework #8 - Fun With Strings
// Solution

// File: strfun.cpp
// Contains definitions of string manipulation functions described in strfun.h

#include "strfun.h"
#include <cassert>
#include <cctype>

namespace m330 {

// length finds the length of s
int length(const char * s)
{
	int L = 0;

	while(*s != '\0')
	{
		L++;
		s++;
	}

	return L;
}

// strpos returns the index of the first occurrence of b in s
int strpos(const char * s, char b)
{
	for(int i = 0; *s != '\0'; i++)
	{
		if(*s == b)
			return i;
		s++;
	}

	return -1;
}

// revstr returns the string s, reversed
void revstr(char * s)
{
	int L = length(s);

	char * rev = s;	//make a new pointer to the first character in s
	char temp;		//temporary swapping variable

	rev += (L-1);		//move rev to the end of s

	for(int i=0; i <= L/2; i++)
	{
		temp = *s;		//switch what rev and s are pointing to
		*s = *rev;
		*rev = temp;
		rev--;			//move rev towards beginning of string
		s++;			//move s towards end
	}

	s = rev;			//bring s back to the beginning
}




// strrpos returns the position of the last occurrence of c in s
int strrpos(const char * s, char c)
{
	int i = 0, pos = 0;

	for(i = 0; s[i] != '\0'; i++)
		pos++;

	for(; i >= 0; i--)
	{
		if(s[pos] == c)
			return pos;
		pos--;
	}

	return -1;
}


// substr makes the substring from positions a through b
void substr(char * s, int a, int b)
{
	int L = length(s);

	assert(a < b);
	assert(b < L);

	//copy the substring
	for(int i=0; i < b - a + 1; i++)
		s[i] = s[a+i];

	//make the rest of the places null
	for(int j = b-a+1; j < L; j++)
		s[j] = '\0';
}


// trim removes whitespace from the beginning and end of s
void trim(char * s)
{
	int L = length(s);

	if(L==0)
		return;

	int begin = 0, end = L-1;

	//find index of first non-whitespace character
	for(int i = 0; i < L; i++)
	{
		if(!isspace(s[i]))
		{
			begin = i;
			break;
		}
	}

	//find index of last non-whitespace character
	for(int j = end; j >= begin; j--)
	{
		if(!isspace(s[j]))
		{
			end = j;
			break;
		}
	}

	//if there's no whitespace, return
	if(begin == 0 && end == 0)
		return;

	substr(s,begin,end);
}


// ucwords capitalizes the first character of each word in s
void ucwords(char * s)
{
	int L = length(s);

	for(int i=0; i < L; i++)
	{
		if(isspace(s[i]) && !isspace(s[i+1]) )
		{
			s[i+1] = toupper(s[i+1]);
		}
	}
}

} // end namespace