0916 编程实验一 词法分析程序

# 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"); else printf("<:, 17>\n"); }break; case '<': { if(a[i+1] == '=') printf("<<=, 21>\n"); else if(a[i+1] == '>') printf("<<>, 22>\n"); else printf("<<, 20>\n"); }break; case '>': { if(a[i+1] == '=') printf("<>=, 24>\n"); else printf("<>, 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; }