Thread: Reading from file into Array

OK, I have a text file that has "1,2,3 d, e, 6,6, h,h, ...etc" I want to put all the digits into an array for analysis. So the array size known. I am able to open the file and filter the desired digits, but I can't seem to store the numbers into the array properly.

In the array I should see "1,2,3,6,6,..." but I dont. Where did I go wrong?

Code:

#include <stdio.h>
#include <ctype.h>

#define ArraySize 40

int ReadDataFromFile(int FileData[ArraySize]);
void IntializeArray(int FileData[ArraySize]);

int main( void ) {
	int i;
	int FileData[ArraySize];
	int count=0;

	IntializeArray(FileData);

	/*useful data in the array*/
	count=ReadDataFromFile(FileData);

	for(i=0;i<count;i++)
		printf("%d",FileData[i]);

	return 0;
}

void IntializeArray(int FileData[ArraySize]){
	int i;
	
	for(i=0;i<ArraySize;i++)
		FileData[i]=1010;
	};

int ReadDataFromFile(int FileData[ArraySize]){
int i;
	
	  FILE *fp = fopen( "testdata", "r" );

  if ( fp ) {
		int ch;

		i=0;
		while ( ( ch = fgetc( fp ) ) != EOF ) {
			if(isdigit(ch)){
				FileData[i]=ch;
				i++;
				}
		}

		fclose( fp );
  } else {
    	perror( "error opening the file" );
  	}
 	return i;
	}

I got the code to open the file from the development section of this forum.

Originally Posted by tabstop

Since "66" is not one character, I would imagine fgetc ("get character from file") would be highly unsuitable for this task. Perhaps some other form of input could be used instead, say perhaps fgets.

oh sorry it should be just one character, it's one character per line.
1
2
3
6
6

I made the change but still, my output is still the same.

If you're testing characters, you probably want '0' and '9', not 0 and 9.


Quzah.

Code:

int main( void ) {
    int i;
    int FileData[ArraySize];
    int count=0;

    IntializeArray(FileData);

    /*useful data in the array*/
    count=ReadDataFromFile(FileData);

    for(i=0;i<count;i++)
        printf("%d",FileData[i]);

	return 0;
}

int ReadDataFromFile(int FileData[ArraySize]){
    int i;
	
    FILE *fp = fopen( "testdata", "r" );

    if ( fp ) {
        ...
    } else {
        perror( "error opening the file" );
    }
    return i;
}

If your fopen call happens to fail, you'll return an uninitialized variable's value back to the main function. This unknown value will then be used to index the array. You're just asking for a segfault. You should probably add a i = 0; line in that section of code where the perror function is. [edit]Or perhaps just initialize i to 0 right from the start.[/edit]

Code:

i=0;
while ( ( ch = fgetc( fp ) ) != EOF ) {
    if((ch >= 0) && (ch <=9) ){
        FileData[i]=ch;
        i++;
    }
}

You are also not doing even just a simple check to ensure that i does not grow to ArraySize or more. You should perhaps modify the condition part of the while loop, maybe add something such that you only enter the loop as long as i is less than ArraySize.