C program not reading characters in lines

Question

I'm trying to read a text file into an array of strings, but struggling. The lines counter works correctly, but it's not making the currentLine expand, and the printf isn't printing anything in any case.

char* readFile() {
    FILE *fp = fopen(inputPath, "r");
    char* currentLine = "";
    char* allLines[] = {};
    int lines = 0;

    do {
        char ch = fgetc(fp);
        printf("%s", ch);
        if (ch == '\n') {
            allLines[lines] = currentLine;
            lines++;
            currentLine = "";
        } else {
            currentLine += ch;
            printf("%s", currentLine);
        }
} while (!feof(fp));



#ifdef debug
for (int i = 0; i < (sizeof(allLines) / sizeof(char*)); i++){
    printf("%d: %s\n", i, allLines[i]);
}
#endif


    fclose(fp);
    return lines;
}

Not sure what to change to fix this? inputPath is just the name of the text file for the time being.

`printf("%s", ch)` invokes undefined behaviour. use `%c` to print `char`s. — babon, Aug 01 '17 at 15:49
[`while (!feof(fp))` is always wrong](https://stackoverflow.com/q/5431941/10077). — Fred Larson, Aug 01 '17 at 15:50
Possible duplicate of [Going through a text file line by line in C](https://stackoverflow.com/questions/9206091/going-through-a-text-file-line-by-line-in-c) — John Szakmeister, Aug 01 '17 at 15:51
`currentLine += ch;` Are you trying to add a character to the end of a c-string? — babon, Aug 01 '17 at 15:55
`currentLine += ch;` -- you can't add characters to a string like that in C. Learn what a 'string' in C really is (a '\0' terminated character array that you have to define somehow, not just a pointer) Take a look at `strcpy()`, `strcat()`, `sprintf()`... — Ingo Leonhardt, Aug 01 '17 at 15:57
@WhozCraig Well, IMHO people coming from other (newer?) languages can be blamed for trying to append something to a c-string with `+=`. :) — babon, Aug 01 '17 at 15:59
Okay I fixed the string appending issue. How would I go about having an array of the strings read in correctly? — , Aug 01 '17 at 16:19
You haven't allocated any space for the current line or for the array of strings. — Jonathan Leffler, Aug 01 '17 at 16:29
You have ask about a runtime problem. However, you have not provided a [mcve] so your question is off topic for stack overflow — user3629249, Aug 02 '17 at 22:28

C program not reading characters in lines

0 Answers0