给我一段使用c++的词法分析器代码

以下是一个简单的使用 C 语言实现的词法分析器的代码示例：

#include <stdio.h>
#include <ctype.h>
#include <string.h>

#define MAX_TOKEN_LEN 100

typedef enum {
    INT, FLOAT, IDENTIFIER, OPERATOR, DELIMITER, KEYWORD
} TokenType;

typedef struct {
    char token[MAX_TOKEN_LEN];
    TokenType tokenType;
} Token;

int isOperator(char c) {
    char operators[] = "+-*/=";
    int i;
    for (i = 0; i < strlen(operators); i++) {
        if (c == operators[i]) {
            return 1;
        }
    }
    return 0;
}

int isDelimiter(char c) {
    char delimiters[] = "();,{}[]";
    int i;
    for (i = 0; i < strlen(delimiters); i++) {
        if (c == delimiters[i]) {
            return 1;
        }
    }
    return 0;
}

int isKeyword(char* token) {
    char keywords[][10] = {"int", "float", "if", "else", "while", "do", "for"};
    int i;
    for (i = 0; i < sizeof(keywords) / sizeof(keywords[0]); i++) {
        if (strcmp(token, keywords[i]) == 0) {
            return 1;
        }
    }
    return 0;
}

Token getNextToken(char* code) {
    Token token;
    int i = 0;
    while (isspace(code[i])) {
        i++;
    }
    if (isalpha(code[i])) {
        while (isalnum(code[i]) || code[i] == '_') {
            token.token[i] = code[i];
            i++;
        }
        token.token[i] = '\0';
        if (isKeyword(token.token)) {
            token.tokenType = KEYWORD;
        } else {
            token.tokenType = IDENTIFIER;
        }
    } else if (isdigit(code[i])) {
        while (isdigit(code[i])) {
            token.token[i] = code[i];
            i++;
        }
        if (code[i] == '.') {
            i++;
            while (isdigit(code[i])) {
                token.token[i] = code[i];
                i++;
            }
            token.tokenType = FLOAT;
        } else {
            token.tokenType = INT;
        }
    } else if (isOperator(code[i])) {
        token.token[0] = code[i];
        token.tokenType = OPERATOR;
        i++;
    } else if (isDelimiter(code[i])) {
        token.token[0] = code[i];
        token.tokenType = DELIMITER;
        i++;
    } else {
        token.token[0] = '\0';
        token.tokenType = -1;
        i++;
    }
    return token;
}

int main() {
    char code[] = "int a = 10; float b = 3.14; if (a > b) { printf(\"a is greater than b\"); }";
    Token token;
    do {
        token = getNextToken(code);
        printf("%s\t%d\n", token.token, token.tokenType);
        code += strlen(token.token);
    } while (strlen(token.token) > 0);
    return 0;
}

这个词法分析器可以处理整型、浮点型、标识符、运算符、分隔符和关键字等各种类型的词法单元。在 `getNextToken` 函数中，通过判断输入代码的第一个字符来确定当前词法单元的类型，并根据类型解析出词法单元的内容。最后，将解析出的词法单元存储到一个 `Token` 结构体中并返回。在主函数中，循环调用 `getNextToken` 函数来逐个输出解析出的词法单元及其类型。