代码展示：分析C中的声明语句

以下语句声明了什么？

1.int(*fun())();

2.int(*foo())[];

3.int(*foo[])();

4.char * const * (*next) ();

5.char *（*c[10])(int **p);

以下的代码帮你分析...

该代码来自<<Expert C Programming>>

 

//代码功能：分析C语言中的声明 //在VS2008中用C编译器编译 //忽略错误处理 //处理结构、枚举和联合时只简单地用"struct","enum"和"union" 来地表它们具体的内容 //假定函数的括号内没有参数列表 #include<stdio.h> #include<string.h> #include<ctype.h> #include<stdlib.h> #define MAXTOKENS 100 //define语句后面没有分号!!! #define MAXTOKENLEN 64 struct token{ char type; char string[MAXTOKENLEN]; }; enum type_tag{ IDENTIFIER, QUALIFIER, TYPE }; int top = -1; struct token stack[MAXTOKENS]; struct token this; //C中并没有this指针，这里this只是一般的变量 #define pop stack[top--] #define push(s) stack[++top] = s enum type_tag classify_string(void) { char *s = this.string; if(!strcmp(s,"const")) { strcpy(s,"read-only"); return QUALIFIER; } if(!strcmp(s,"volatile")) return QUALIFIER; if(!strcmp(s,"void")) return TYPE; if(!strcmp(s,"char")) return TYPE; if(!strcmp(s,"signed")) return TYPE; if(!strcmp(s,"unsigned")) return TYPE; if(!strcmp(s,"short")) return TYPE; if(!strcmp(s,"int")) return TYPE; if(!strcmp(s,"long")) return TYPE; if(!strcmp(s,"float")) return TYPE; if(!strcmp(s,"double")) return TYPE; if(!strcmp(s,"struct")) return TYPE; if(!strcmp(s,"union")) return TYPE; if(!strcmp(s,"enum")) return TYPE; return IDENTIFIER; } //读取下一个标记到"this" void gettoken(void) { char *p = this.string; //略过空白字符 while((*p = getchar()) == ' '); if(isalnum(*p)) //Tests whether an element in a locale is an alphabetic or a numeric character. { //读入的标识符以A-Z,0-9开头 while(isalnum(*++p = getchar())); ungetc(*p,stdin); //Pushes a character back onto the stream and clears the end-of-file indicator. *p = '/0'; this.type = classify_string(); return; } if(*p == '*') { strcpy(this.string,"pointer to"); this.type = '*'; return; } this.string[1] = '/0'; this.type = *p; return; } //理解所有分析过程的代码段 read_to_first_identifier() { gettoken(); while(this.type != IDENTIFIER) { push(this); gettoken(); } printf("%s is ",this.string); gettoken(); } deal_with_array() { while(this.type == '[') { printf(" array "); gettoken(); if(isdigit(this.string[0])) { printf("0..%d",atoi(this.string)-1); gettoken(); } gettoken(); printf("of "); } } deal_with_function_args() { while(this.type != ')') gettoken(); gettoken(); printf(" function returning "); } deal_with_pointers() { while(stack[top].type == '*') { printf("%s " , pop.string); } } deal_with_declarator() { //处理标识符之后可能存在的数组/函数 switch(this.type) { case '[' : deal_with_array(); break; case '(' : deal_with_function_args(); break; } deal_with_pointers(); /*处理在读入到标识符之前压入到堆栈中的符号*/ while(top >= 0) { if(stack[top].type == '(') { pop; gettoken(); deal_with_declarator(); } else { printf("%s " , pop.string); } } } int main() { //将标记压入堆栈中，知道遇见标识符 read_to_first_identifier(); deal_with_declarator(); printf("/n"); return 0; } 

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