我曾经在Linux上写的一个C程序，借助Lex做词法分析来同时统计N个文本文件的字符数，单词数和行数。让我觉得Lex确实挺有意思的。确实Lex的功能非常强大，用来做小巧的词法分析非常适合，也非常好用。这个程序参考了《Lex与Yacc》上的一个例子。
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%{ unsigned int char_count = 0, word_count = 0, line_count = 0; %} %%[^ /t/n]+ {word_count++; char_count+=yyleng;}; /n {char_count++; line_count++;}; . char_count++; %%char **file_list; unsigned int current_file = 0; unsigned int total_file = 0; unsigned int total_cc = 0; unsigned int total_wc = 0; unsigned int total_lc = 0; typedef struct file_info{ unsigned int c; unsigned int w; unsigned int l; char *name; }INFO; INFO **all; int create_info(int num) { INFO *tmp; int i; if (num <= 0){ return -1; } all = (INFO **)malloc(sizeof(int *)*num); for (i = 0; i < num; i++){ tmp = (INFO *)malloc(sizeof(INFO)); tmp->c = 0; tmp->w = 0; tmp->l = 0; tmp->name = NULL; all[i] = tmp; } return 1; } int delete_info(int num) { int i; if ((all == (INFO **)0) || num <= 0){ return -1; } for (i = 0; i < num; i++){ free(all[i]); } free(all); return 1; } int set_info(int pos) { int length = 0; if (pos < 0){ return -1; } all[pos]->c = char_count; all[pos]->w = word_count; all[pos]->l = line_count; all[pos]->name = file_list[pos]; return 1; } int main(int argc, char** argv) { FILE *file; int position = 0; int i; file_list = argv + 1; total_file = argc - 1; current_file = 0; printf("--------------------------------------------------------------/n", total_file); if (argc > 1){ if (create_info(total_file) == -1){ fprintf(stderr, "%s/n", "Encounter a error when malloc memory."); exit(1); } } if (argc == 2){ file=fopen(argv[1], "r"); if (!file){ fprintf(stderr, "Could not open %s./n", argv[1]); delete_info(total_file); exit(1); } yyin = file; } yywrap(); yylex(); if (argc > 1){ total_cc += char_count; total_wc += word_count; total_lc += line_count; if (set_info(current_file-1) == -1){ fprintf(stderr, "%s/n", "Encounter a error when set information to INFO."); delete_info(total_file); exit(1); } for (i = 0; i < total_file; i++){ printf("char:%-8lu word:%-8lu line:%-8lu file name:%s/n", all[i]-> c, all[i]->w, all[i]->l, file_list[i]); } printf("----------------------- total --------------------------------/n"); printf("chars:%-8lu words:%-8lu lines:%-8lu files:%d/n", total_cc, tot al_wc, total_lc, total_file); }else{ printf("char:%-8lu word:%-8lu line:%-8lu/n", char_count, word_count, l ine_count); } delete_info(total_file); return 0; } yywrap() { FILE *file = NULL; if ((current_file > 0) && (current_file < total_file) && (total_file > 1)) { total_cc += char_count; total_wc += word_count; total_lc += line_count; if (set_info(current_file-1) == -1){ fprintf(stderr, "%s/n", "Encounter a error when set information to INFO."); delete_info(total_file); exit(1); } char_count = word_count = line_count = 0; fclose(yyin); } while ((file_list[current_file] != (char *)0) && (current_file < total_fil e)){ file = fopen(file_list[current_file++], "r"); if (!file){ fprintf(stderr, "could not open %s .", file_list[current_file - 1] ); }else{ yyin = file; break; } } return (file? 0 : 1); } |
