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#include <stdio.h>
#define OUT 0
#define FALSE -1
#define TRUE 1
#define STAR 1
#define SLASH 2
void count(char input, int* parentheses, int* brackets, int* braces);
/* this is a c programm to detect syntax errors in c programms */
int
main(void)
{
char input;
int temp, state, line, parentheses, brackets, braces, single_quotes, double_quotes, double_quotes_line;
state = OUT;
parentheses = brackets = braces = single_quotes = double_quotes = double_quotes_line = 0;
line = 1;
while ((input = getchar()) != EOF) {
if (input == '\n') {
line++;
continue;
}
/* filiter out comments */
else if (input == '/') {
temp = input;
if ((input = getchar()) == '*') {
state = STAR;
temp = FALSE;
}
else if (input == '/') {
state = SLASH;
temp = FALSE;
}
}
else if (input == '*' && state == STAR) {
if ((input = getchar()) == '/') {
state = OUT;
continue;
}
}
else if (input == '\n' && state == SLASH) {
state = OUT;
continue;
}
if (temp != FALSE)
count(temp, &parentheses, &brackets, &braces);
if (state == OUT) {
if (input == '"' && double_quotes == TRUE) {
double_quotes = FALSE;
continue;
}
/* process escape sequences */
else if (input == '\\') {
input = getchar();
if (input == '\n') {
line++;
continue;
}
if (input != 'a' && input != 'b' && input != 'f' && input != 'n' && input != 'r' &&
input != 't' && input != 'v' && input != '\\' && input != '\'' && input != '"' && input != '?' && input != '0')
printf("unproper escape sequence detected at line %d\n", line);
else if (input == 'o') {
if((input = getchar()) != 'o' || (input = getchar()) != 'o')
printf("unproper escape sequence detected at line %d\n", line);
}
else if (input == 'x') {
if((input = getchar()) != 'h' || (input = getchar()) != 'h')
printf("unproper escape sequence detected at line %d\n", line);
}
else
continue;
}
/* process double quotes */
else if (input == '"') {
double_quotes = TRUE;
double_quotes_line = line;
}
/* process single quotes */
else if (input == '\'' && double_quotes != TRUE) {
;
if ((input = getchar()) == '\\') {
input = getchar();
}
if ((input = getchar()) != '\'')
printf("unproper single quotes detected at line %d\n", line);
continue;
}
/* process all others */
count(input, &parentheses, &brackets, &braces);
}
}
if (parentheses%=2)
printf("unproper parentheses detected\n");
if (brackets%=2)
printf("unproper brackets detected\n");
if (braces%=2)
printf("unproper braces detected\n");
if (double_quotes == TRUE)
printf("unproper double quotes detected at line %d\n", double_quotes_line);
return 0;
}
void
count(char input, int* parentheses, int* brackets, int* braces)
{
switch (input) {
case '(' :
(*parentheses)++;
break;
case ')' :
(*parentheses)--;
break;
case '[' :
(*brackets)++;
break;
case ']' :
(*brackets)--;
break;
case '{' :
(*braces)++;
break;
case '}' :
(*braces)--;
break;
}
}
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