编译原理实验之词法分析

内容有更新哦~~~

能识别小数，科学记数法表示的数，负数亦可。

不多解释，代码先上：

#include <cstdio>#include <iostream>#include <string>#include <cstring>#include <algorithm>#include <cctype>#include <fstream>#include <map>#include <cstdlib>#include <cmath>using namespace std;const int maxn = 1002;const int n_key = 40;const int n_oper = 21;char c;string key_word[n_key] = {"auto", "enum", "restrict", "unsigned", "break",                    "extern", "return", "void", "case", "float",                    "short", "volatile", "char", "for", "signed",                    "while", "const", "goto", "sizeof", "_Bool",                    "continue", "if", "static", "_Complex", "default",                    "inline", "struct", "_Imaginary", "do", "int",                    "switch", "double", "long", "typedef", "else",                    "register", "union", "main", "scanf", "printf"};string oper[] = {"+", "-", "*", "/", "^",                "<", ">", "++", "--", "==",                "*=", "/=", ">=", "<=", "<<",                ">>", ">>=", "<<=", "%", "&",                "^"};char bound[] = {',', ';', '(', ')', '[', ']', '{', '}'};struct Word{                //词结构体    int id;    string value;};struct Num{    int id;    int vi;    double vd;};Num n[maxn];        //数字Word w[maxn];       //词map<string, int> m;    //标识符int f = 0, ff = 0;bool is_oper(string s){    for(int i=0; i<n_oper; i++) if(s == oper[i]) return true;    return false;}bool is_bound(char c){    for(int i=0; i<sizeof(bound); i++) if(c == bound[i]) return true;    return false;}bool is_key(string s){    for(int i=0; i<n_key; i++) if(s == key_word[i]) return true;    return false;}int stoi(string s){                         //get int    int ans = 0;    for(int i=0; i<s.size(); i++) ans = ans * 10 + s[i] - '0';    return ans;}double stof(string s){                      //get double    long long ans = 0;    int fd = -1, fe = -1;    for(int i=0; i<s.size(); i++){        if(s[i] == '.'){            fd = i;            continue;        }        if(s[i] == 'e'){            fe = i;            continue;        }        ans = ans * 10 + s[i] - '0';    }    if(fd != -1 && fe == -1) return double(ans)/(pow(10, s.size() - fd - 1));    else if(fd == -1 && fe != -1){        long long temp = ans % (long long)pow(10, s.size() - fe - 1);     //得到e后的数字        ans /= pow(10, s.size() - fe - 1);                                //得到e前的数字        return double(ans*pow(10, temp));    }    else{        long long temp = ans % (long long)pow(10, s.size() - fe - 1);     //得到e后的数字        ans /= pow(10, s.size() - fe - 1);                                //得到e前的数字        long long tt = (s.size() - fd - 1) - (s.size() - fe - 1) - 1;     //得到.后的数字        return (double)ans/pow(10, tt) * (pow(10, temp));    }}void getword(char filename[]){    freopen(filename, "r", stdin);              //重定向    string str = "";    int flag, is_end;    is_end = scanf("%c", &c);    while(is_end != EOF){        flag = 0;        if(isspace(c)){            str = "";            while(isspace(c) && is_end != EOF){   //滤空格                is_end = scanf("%c", &c);            }        }        if(isalpha(c)){                         //以字母开头            str = "";            while(isalnum(c) || c == '_'){                str += c;                is_end = scanf("%c", &c);            }            w[++f].value = str;            if(is_key(str)) w[f].id = 1;        //保留字            else{                w[f].id = 2;                     //标识符                m[str] ++;            }            flag = 1;        }        if(isdigit(c)){                          //数字            int fd = 0, fe = 0, fflag = 0, is_neg = 0;            if(str == "-") is_neg = 1;            str = "";            while(isdigit(c) || c == '.' || c == 'e'){                if(c == '.') fd ++;                if(c == 'e') fe ++;                if(c == '.' && fe) fflag = 1;                str += c;                is_end = scanf("%c", &c);            }            if(str[str.size()-1] == '.' || str[str.size()-1] == 'e') fflag = 1;            if(fflag){                cout<<"错误-->不合法数字："<<(is_neg ? "-" + str : str)<<endl;    //忽略不合法输入            }            else{                if(!fd && !fe){                    n[++ff].vi = (is_neg ? -stoi(str) : stoi(str));                    n[ff].id = 1;                }                else{                    n[++ff].vd = (is_neg ? -stof(str) : stof(str));                    n[ff].id = 2;                }                w[++f].id = 3;  w[f].value = (is_neg ? "-" + str : str);            }            flag = 1;        }        if(is_bound(c)){            //界符            str = "";            str += c;            w[++f].value = str;            w[f].id = 4;            is_end = scanf("%c", &c);            flag = 1;        }        string ss = "";        ss += c;        if(is_oper(ss)){            bool is_lastdigt = isdigit(str[str.size()-1]);            str = "";            while(is_oper(ss)){                str += c;                is_end = scanf("%c", &c);                ss += c;            }            if(str == "-" && !is_lastdigt && isdigit(c)) continue;            if(is_oper(str)){                w[++f].value = str;                w[f].id = 5;            }            flag = 1;        }        if(!flag && is_end != EOF){            str = "";            str += c;            w[++f].value = str;            w[f].id = 6;            is_end = scanf("%c", &c);        }    }    freopen("CON", "r", stdin);           //关闭重定向,恢复标准}void to_file1(){                        //主表    char filename[20];    puts("请输入词法分析主表要保存到的地址：");    scanf("%s", filename);    fstream out;    out.open(filename, ios::out);    out<<"1.保留字   2.标识符   3.数字   4.界符   5.操作符   6.其他"<<endl<<endl;    for(int i=1; i<=f; i++) out<<w[i].id<<"  "<<w[i].value<<endl;    out.close();}void to_file2(){                        //标识符表    ofstream out;    char filename[20];    puts("请输入词法分析标识符表要保存到的地址：");    scanf("%s", filename);    out.open(filename, ios::out);    map<string, int>::iterator it;    for(it=m.begin(); it!=m.end(); it++) out<<it->first<<endl;    out.close();}void to_file3(){                        //数字表    ofstream out;    char filename[20];    puts("请输入词法分析数字表要保存到的地址：");    scanf("%s", filename);    out.open(filename, ios::out);    out<<"1.int   2.double"<<endl<<endl;    for(int i=1; i<=ff; i++) out<<n[i].id<<"  "<<(n[i].id == 1 ? n[i].vi : n[i].vd)<<endl;    out.close();}int main(){    char filename[20];    puts("请输入您要打开的文件地址：");    scanf("%s", filename);    getword(filename);    to_file1();    to_file2();    to_file3();    return 0;}

编译原理之词法分析实验终于写完了，收工啦~~~

PS:本人还是比较满意的o(^▽^)o