C++_面试题_21_字符串操作

1. 统计字符串出现的次数

#include <iostream>
#include <cstring>

struct WordCount
{
char word[32];
int count;
};

int main()
{
char s[] = "hello word start begin hello go test hello word";
WordCount wc[100];     // 最多 100 个不同单词
int wc_size = 0;

    char* p = s;

    while (*p)
{
//跳过空格
while (*p == ' ')
p++;
//读取一个单词
char token[32];
int idx = 0;

        while (*p && *p != ' ')
{
token[idx++] = *p;
p++;
}
token[idx] = '\0';
if (idx == 0) continue;  //避免末尾空白

        //判断token 是否已经出现
bool found = false;

        for (int i = 0; i < wc_size; i++)
{
if (strcmp(wc[i].word, token) == 0)
{
wc[i].count++;
found = true;
break;
}
}

        //新单词
if (!found)
{
strcpy_s(wc[wc_size].word, token);
wc[wc_size].count = 1;
wc_size++;
}
}

    //输出结果
for (int i = 0; i < wc_size; i++)
{
std::cout << wc[i].word << ":" << wc[i].count << std::endl;
}

    return 0;
}

#include <iostream>
#include <string>
using namespace std;
std::string replaceSpaces(const std::string& input,
const std::string& replacement) {
std::string output;
for (char c : input) {
if (c == ' ') {
output += replacement;
}
else
{
output += c;
}
}
return output;
}

int main()
{
std::string input = "Hello World! Welcome to C++  programming.";
std::string replaced = replaceSpaces(input, "%20");
std::cout << "Original string: " << input <<
std::endl;
std::cout << "Replaced string: " << replaced <<
std::endl;
return 0;
}