根据CSV数据构造一个C数组

Question

So, I am trying to build ac program to be able to read star catalogues and store them in arrays for further analysis.

Star catalogues usually come in .csv format and have a LOT of data on them, also some slots are empty and not all of them have int, double or float type data .

I want this program to be able to read "any" star catalogue (or by that matter any .csv file).

My first aproaches to construct such program met the issue that arrays must have their sizes declared, I decided to bypass this by creating a line and column counter functions, to be implemented by the main function.

int* getfield(char* line){
    FILE *fp = fopen("./hipparcos.csv", "r");
    int ch;
    int lines=0;
    do{
        ch = fgetc(fp);
        if( ch== '\n'){
            lines++;    
        }    
    }while( ch != EOF );    

    printf("number of lines in the file %d\n",lines);
    return lines;
}

which does work well when implemented in the main function like this getfield("\\n"); so I get to see how many lines it is reading in the terminal (therefore know its counting them somehow).

What I need is to know how to store that quantity as a variable to later declare the array size and store lines in every position, and maybe after that do a line split (and separate each line into every column).

Any insights into how to proceed or a more efficient approach is appreciated.

Answer 1

You returns just int value, so change header of function to

int getfield(char* line){

this should not be a pointer.

Also consider possibility of not presence of '\\n' at the end of the last line of the file (in this case you will have result 1 less than the number of rows).

EDIT:

If you just want to count number of lines as number of '\\n' characters changed function is as follows:

int getCharCount(char chr){
    FILE *fp = fopen("./hipparcos.csv", "r");
    int ch;
    int lines = 0;
    do{
        ch = fgetc(fp);
        if( ch == chr){
            lines++;   
        }    
    }while( ch != EOF );
    fclose(fp); 
    return lines;
}

you can call this from main() eg:

    printf("number of lines in the file %d\n", getCharCount('\n')); // maybe +1 needed :-)

but I understand that it is a draft of your program, so consider as an option sending file name as a parameter to your function. This make your solution more flexible.