编译原理C语言实现语法分析

C语言的语法分析是编译原理中的重要内容，通常使用自顶向下的递归下降分析法来实现。下面是一个简单的C语言语法分析的示例：

#include <stdio.h>
#include <stdlib.h>

void match(char expectedToken);
void program();
void declarationList();
void declaration();
void statementList();
void statement();
void expression();
void term();
void factor();

int lookahead;
char expr[100];

int main() {
    printf("Enter an arithmetic expression: ");
    scanf("%s", expr);
    
    lookahead = expr[0];
    program();

    if (lookahead == '\0') {
        printf("Parsing successful.\n");
    } else {
        printf("Parsing failed.\n");
    }

    return 0;
}

void match(char expectedToken) {
    if (lookahead == expectedToken) {
        lookahead = expr[++index];
    } else {
        printf("Error: Unexpected token.\n");
        exit(1);
    }
}

void program() {
    declarationList();
    statementList();
}

void declarationList() {
    declaration();

    while (lookahead == ',') {
        match(',');
        declaration();
    }

    match(';');
}

void declaration() {
    if (lookahead == 'int') {
        match('int');
    } else if (lookahead == 'float') {
        match('float');
    } else {
        printf("Error: Expected int or float.\n");
        exit(1);
    }

    // TODO: Handle variable name
}

void statementList() {
    statement();

    while (lookahead == ';') {
        match(';');
        statement();
    }
}

void statement() {
    // TODO: Handle statements
}

void expression() {
    term();

    while (lookahead == '+' || lookahead == '-') {
        match(lookahead);
        term();
    }
}

void term() {
    factor();

    while (lookahead == '*' || lookahead == '/') {
        match(lookahead);
        factor();
    }
}

void factor() {
    if (lookahead == '(') {
        match('(');
        expression();
        match(')');
    } else if (isdigit(lookahead)) {
        match(lookahead);
    } else {
        printf("Error: Expected number or (.\n");
        exit(1);
    }
}

上面的代码实现了一个简单的C语言的语法分析器，可以对输入的算术表达式进行语法分析。在实际的编译器实现中，还需要考虑更多的细节和语法规则，这里只是一个简单示例。