C_checker

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

bool checkbrackets(char* astr, char first, char second){
    int cntopened = 0;
    for (int i = 0; astr[i] != '\0'; ++i){
        if (astr[i] == first) cntopened++;
        else if (astr[i] == second) cntopened--;
        if (cntopened < 0) break;
    }
    return (cntopened == 0);
}

int checkcomments(char* astr){
/* 0 - no comments or closed comment
 * 1 - only opened comment
 * 2 - only closed comment*/
    int res = 0;
    for (int i = 0; astr[i] != '\0'; ++i){
        if ((astr[i] == '/') && (astr[i+1] == '*')){
            res = 1;
            astr[i] = '(';
            astr[i+1] = '(';
        }
        if ((astr[i] == '*') && (astr[i+1] == '/')){
            if (res == 1) res = 0; else res = 2;
            astr[i] = ')';
            astr[i+1] = ')';
        }
    }
    return res;
};

bool checkescapesequence(char* astr){
    bool res = true;
    for (int i = 0; astr[i] != '\0'; ++i){
        if (astr[i] == '\\') {
            switch (astr[i + 1]) {
                case 'a': break;
                case 'b': break;
                case 'f': break;
                case 'n': break;
                case 'r': break;
                case 't': break;
                case 'v': break;
                case '\'': break;
                case '"': break;
                case '?': break;
                default:
                    return false;
            }
        }
    }
    return res;
}

int main(){
    char* s = malloc(80*sizeof(char));
    FILE *f = fopen("input.txt","r");
    int commentscnt = 0;
    for (int i  = 1; !feof(f); i++) {
        fscanf(f, "%s", s);
        bool res;
        res = checkbrackets(s,'(',')');
        printf(res ? "" : "Error: line %d brackets type () disbalance \n",i);
        res = checkbrackets(s,'{','}');
        printf(res ? "" : "Error: line %d brackets type {} disbalance \n",i);
        res = checkbrackets(s,'[',']');
        printf(res ? "" : "Error: line %d brackets type [] disbalance \n",i);
        res = checkbrackets(s,'"','"');
        printf(res ? "" : "Error: line %d brackets type \"\" disbalance \n",i);
        res = checkbrackets(s,'\'','\'');
        printf(res ? "" : "Error: line %d brackets type \'\' disbalance \n",i);
        res = checkescapesequence(s);
        printf(res ? "" : "Error: line %d incorrect escape sequence \n",i);
        switch (checkcomments(s)){
            case 1: commentscnt += 1; break;
            case 2: commentscnt -= 1; break;
            default: break;
        }
    }
    printf(commentscnt ? "Error: comments disbalance \n" : "");
    return 0;
}