strange behaviour in output - c

Question

I have a problem with my program to get it run correctly.
here is the code:
#include <stdio.h>
#include <stdlib.h> // for EXIT_SUCCESS and EXIT_FAILURE
#include <ctype.h>
#include <string.h>
void ReadFile(FILE* file) {
unsigned lines = 0;
int braces = 0;
int curlyBraces = 0;
int comments = 0;
int c;
char* line = 0;
unsigned col = 0;
while ((c = fgetc(file)) != EOF) {
if(c == '\n') { // new line
lines++;
printf("%4d: {%d} (%d) /*%d*/ |%s\n", lines, curlyBraces, braces, comments, line);
free(line); line = 0;
col = 0;
} else {
// add character to line
line = (char*)realloc(line, (col+1)*sizeof(char));
if (line == 0) {
fprintf(stderr, "error reallocating memory");
return;
}
line[col] = c;
col++;
if (c == '(') {
braces++;
} else if (c == ')') {
braces--;
} else if (c == '{') {
curlyBraces++;
} else if (c == '}') {
curlyBraces--;
} else if (c == '/') {
if (fgetc(file) == '*') {
comments++;
} else {
fseek(file, -1, SEEK_CUR);
}
} else if (c == '*') {
if (fgetc(file) == '/') {
comments--;
} else {
fseek(file, -1, SEEK_CUR);
}
}
}
}
}
int main(int argc, char** argv) {
short lines = 0, words = 0, chars = 0;
/* check for arguments */
if (argc == 1) {
fprintf(stderr, "usage: %s filename\n", argv[0]);
return EXIT_FAILURE;
}
/* open file */
FILE* file = fopen(argv[1], "r");
if(file == 0) {
fprintf(stderr, "error open file '%s'\n", argv[1]);
return EXIT_FAILURE;
}
ReadFile(file);
if (fclose(file) == EOF) {
fprintf(stderr, "error in fclose()\n");
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
on the output i get some weird output, like realloc overwrites some data...
i already tried strcat, but i can't use constant chars. so i have to use realloc.
here is a short excerpt of the output
P 68: {1} (0) /*0*/ | / open file *
69: {1} (0) /*0*/ | FILE* file = fopen(argv[1], "r");
70: {2} (0) /*0*/ | if(file == 0) {
rn EXIT_FA(0) /*0*/ | fprintf(stderr, "error open file '%s'\n", argv[1]);
r open fi (0) /*0*/ | return EXIT_FAILURE;
73: {1} (0) /*0*/ | }
} 74: {1} (0) /*0*/ |
maybe there is another way to reaize this? with fgets() i could get the whole line, but increments the pointer in the file and i have to give fgets() a count of chars. so that wouldn't be the perfect solution.

Answer 1

You need to terminate your string before you print it out:
lines++;
line[col] = 0; // new
printf("%4d: {%d} (%d) /*%d*/ |%s\n", lines, curlyBraces, braces, comments, line);
Unfortunately line[col] is out of bounds here. So you need realloc line before adding the terminator like this:
lines++;
line = (char*)realloc(line, (col+1)*sizeof(char));
if (line == 0) {
fprintf(stderr, "error reallocating memory");
return;
}
line[col] = 0; // new
printf("%4d: {%d} (%d) /*%d*/ |%s\n", lines, curlyBraces, braces, comments, line);
Also, do you know about ungetc? You can replace those fseek(-1) with ungetc.