来得有点晚的词法分析

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

int panduan(char tmp[]){char b[6][10] = {"begin", "if", "then", "while", "do", "end", };int k = 0;

while(k < 6) // 临时变量tmp 与 字符串b[k] 进行比较{if(strcmp(tmp, b[k]) == 0){printf("<%s, %d>\n", tmp, k+1);return 0;}k++;}printf("<%s, 10>\n", tmp);

return 0;}

void cifafenxi(char a[]){int i = 0, j = 0;char tmp[10];int flag = 0;

while(a[i] != '\0'){if(a[i] >= 'a' && a[i] <= 'z') // 判断标识符{tmp[j] = a[i];j++;while((a[i+1] >= 'a' && a[i+1] <= 'z') || (a[i+1] >= '0' && a[i+1] <= '9')){i++;tmp[j] = a[i];j++;}tmp[j] = '\0';j = panduan(tmp);}

if(a[i] >= '0' && a[i] <= '9') // 判断数字{tmp[j] = a[i]; j++;while(a[i+1] >= '0' && a[i+1] <= '9'){i++;tmp[j] = a[i];j++;}tmp[j] = '\0';printf("<%s, 11>\n", tmp);j = 0;}

switch(a[i]) // 判断符号{case '+':printf("<+, 13>\n");break;case '-':printf("<-, 14>\n");break;case '*':printf("<*, 15>\n");break;case '/':printf("</, 16>\n");break;case ':':{if(a[i+1] == '=')printf("<:=, 18>\n");elseprintf("<:, 17>\n");}break;case '<':{if(a[i+1] == '=')printf("<<=, 21>\n");else if(a[i+1] == '>')printf("<<>, 22>\n");elseprintf("<<, 20>\n");}break;case '>':{if(a[i+1] == '=')printf("<>=, 24>\n");elseprintf("<>, 23>\n");}break;case '=':printf("<=, 25>\n");break;case ';':printf("<;, 26>\n");break;case '(':printf("<(, 27>\n");break;case ')':printf("<), 28>\n");break;case '#':printf("<#, 0>\n");break;}i++;}}

int main(void){char a[300];

printf("input : ");gets(a);cifafenxi(a);

return 0;}

转载于:https://www.cnblogs.com/ben-9527/p/5961075.html