第一个仅仅出现一次的字符 代码(C)

本文地址: http://blog.csdn.net/caroline_wendy

题目: 在字符串中找出第一个仅仅出现一次的字符.

字符是char类型, 所以匹配256种可能, 採用hash表, 计算出现的次数, 再找到第一次出现的字符.

代码:

/*

 * main.cpp

 *

 *  Created on: 2014.6.12

 *      Author: Spike

 */

/*eclipse cdt, gcc 4.8.1*/

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

char FirstNotRepeatingChar (char* pString) {

	if (pString == NULL)

		return '\0';

	const int tableSize = 256;

	unsigned int hastTable[tableSize];

	for (unsigned int i=0; i<tableSize; ++i)

		hastTable[i] = 0;

	char* pHashKey = pString;

	while (*pHashKey != '\0')

		hastTable[*(pHashKey++)]++;

	pHashKey = pString;

	while (*pHashKey != '\0') {

		if (hastTable[*pHashKey] == 1)

			return *pHashKey;

		pHashKey++;

	}

	return '\0';

}

int main(void)

{

	char pString[] = "abaccdeff";

	char result =  FirstNotRepeatingChar (pString);

    printf("result = %c\n", result);

    return 0;

}

输出:

result = b