pex2_13.cpp

数据结构C++代码,经典代码,受益多多,希望大家多多支持

#include <iostream.h>
#include <strstream.h>
#include <fstream.h>

// start at char p and skip all blanks in a character array.
// return a pointer to the next non-blank char and NULL if
// the NULL character is encountered (end of string)
char *SkipWhiteSpace(char *p)
{
	// return if the string is empty
	if (*p == NULL)
		return NULL;
	// look for a non-blank character
	while(*p == ' ')
		p++;

	if (*p == NULL)
		// all remaining characters in the array are blank
		return NULL;
	else
		// return the address of the non-blank character
		return p;
}
	
void main(void)
{
	char line[82], outstring[128];
	char *p;
	int numx;
	ofstream fout;
	
	fout.open("funcs.val");
	
	// read lines until end of file
	while(cin.getline(line,82,'\n'))
	{
		// declare an output array local to the block. each
		// iteration of the while will create a new outs
		ostrstream outs(outstring, sizeof(outstring));

		// output "FuncName(x)"
		outs << line[0] << "(x) = ";
		// skip leading blanks
		p = SkipWhiteSpace(&line[1]);
		numx = 0;
		// cycle through string and build the array
		while(p != NULL)
		{
			// for each 'x', increment numx
			if (*p == 'x')
				numx++;
			else
			{
				// a + or - found
				if (numx > 1)
					// output x**numx to array
					outs << "x**" << numx << " ";
				else
					// output "x"
					outs << "x ";
				// write out the + or -
				outs << *p << " ";
				// starting a new collection of x's
				numx = 0;
			}
			// find next non-blank char or end of string
			p = SkipWhiteSpace(p+1);
		}
		// output trailing term
		if (numx > 1)
			outs << "x**" << numx << " ";
		else
			outs << "x ";
		outs << ends;
		// write formatted array to file
		fout << outstring << endl;
	}
}

/*
<Run>

F x x x + x x - x
G x x - x x x + x x x x
H x + xxxxx - xxxxxxx + xx x

<output file "funcs.val">
F(x) = x**3 + x**2 - x 
G(x) = x**2 - x**3 + x**4 
H(x) = x + x**5 - x**7 + x**3 
*/