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。
%{
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);
}
