Reading Input into Array

Question

I am trying to read a series of 8 integers from a file into an array then display those integers. I keep getting a segmentation fault the third time around, and I can't quite figure out what I am doing wrong.

struct aStruct {
    int a;
    int b;
    ...
};

typedef struct aStruct myStruct; 

while(fgets(line, MAX_LENGTH, file) != NULL) {
    int myArray[8] = {0};
    char* val = strtok (line," ,\n\t\r");
    while (val != NULL)
    {
        myArray[i] = atoi(val);
        i++;
        val = strtok (NULL, " ,\n\t\r");
    }

    myStruct foo;

    foo.a = myArray[0];
    foo.b = myArray[1];
            ...
}

The input file is structured like so:

0, 0, 1, 5, 0, 0, 0, 0
1, 0, 2, 5, 0, 0, 0, 0
2, 0, 3, 5, 0, 0, 0, 0
3, 0, 4, 5, 0, 0, 0, 0
4, 0, 5, 5, 0, 0, 0, 0

When tested with:

printf("myArray[0]: %d ", myArray[0]);

I get an odd output of 0 0

Where I believe it should be 0 1. Am I not initializing something correctly, or is my new syntax incorrect for the struct? I've tried a few different combinations, cant quite figure it out.

Compile with all warnings and debugging info (e.g. g++ -Wall -g) and use a debugger (e.g. gdb); also new is a C++ keyword (not a C one). So you should tag your question as C++ (and improve your code to be more genuine C++, probably using std::vector ..). Also show more code, notably declaration of myStruct ... — Basile Starynkevitch
– Basile Starynkevitch, Commented Nov 13, 2013 at 23:13
Sorry. I was unaware that new is a C++ keyword. I am trying to write this all in C, so perhaps I should switch that around. — Frank Johnson
– Frank Johnson, Commented Nov 13, 2013 at 23:18
Then your code is not C and should not compile with a standard C compiler (unless if new is some very weird macro, you should show its definition). — Basile Starynkevitch
– Basile Starynkevitch, Commented Nov 13, 2013 at 23:18

dkz · Accepted Answer · 2013-11-13 23:18:38Z

4

I think your problem here is in uninitialized or non reset i variable. Adding i = 0 inside your while-loop might help.

while(fgets(line, MAX_LENGTH, file) != NULL) {
    i = 0; // <<< reseting array index
    int myArray[8] = {0};
    char* val = strtok (line," ,\n\t\r");
    while (val != NULL)
    {
        //...
        i++;
    }
}

answered Nov 13, 2013 at 23:18

dkz

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1 Comment

Frank Johnson Over a year ago

Ah! I'm blind. I knew it was something small. Thank you!

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