Question about reading int and String from array

Question

I have two-dimensional arrays which contain the input from a file. I want to assign integers and strings from the array to different variables; the integer is set correctly, but the string is not working.

the input is like:

(1,2) apple 2 3 north

but all these information are inside:

char data[MAX_LINES][MAX_LEN];

I am trying to use sscanf to assign values:

sscanf(data[i],"(%d,%d) %8s %d %d %8s",&x,&y,type,&age,&hun,direction);

Code structure by ignoring unrelated code

    FILE *in_file = fopen(fileName,"r");
    char data[MAX_LINES][MAX_LEN];
    int x,y,age,hun;
    char type[10];
    char deriction[20];
    if(! in_file){
        printf("cannot read file\n");
        exit(1);
    }
    int line=0;
    while(!feof(in_file) && !ferror(in_file)){
        if(fgets(data[line],MAX_LEN,in_file) !=NULL ){
            char *check = strtok(data[line],d);
            
            line++;
        }
    }
    fclose(in_file);
    for(int i = 9; i<14;i++){
        sscanf(data[i],"(%d,%d) %8s %d %d %8s",&x,&y,type,&age,&hun,deriction);
}

You should check the return value of `scanf()` to ensure that it's parsing the input correctly. — Barmar, Dec 27 '22 at 21:08
Please show the declarations of all the variables you're reading into. — Barmar, Dec 27 '22 at 21:14
See [`while (!feof(file))` is always wrong](https://stackoverflow.com/q/5431941/15168) for a discussion of why it is a bad idea to use `feof()` (or `ferror()`, or both) in a loop control. Test the input function result directly, not the flags used by `feof()` and `ferror()`. — Jonathan Leffler, Dec 27 '22 at 21:43
What is _magical_ about lines 9-13 that those are selected for printing??? — Fe2O3, Dec 27 '22 at 22:02

score 0 · Answer 1 · answered Dec 27 '22 at 21:22

#include <stdio.h>
int main(){
    //Data:
    char data[1][100] = {"(1,2) apple 2 3 north"};
    
    //Define variables:
    int x, y, age, hun;
    char type[10], direction[10];
    
    sscanf(data[0], "(%d,%d) %s %d %d %s", &x, &y, type, &age, &hun, direction);

    //Check by printing it out:
    printf("(%d,%d) %s %d %d %s\n", x, y, type, age, hun, direction);
    printf("x: %d\ny: %d\ntype: %s\nage: %d\nhun: %d\ndirection: %s", x, y, type, age, hun, direction);

    //Success:
    return 0;
}

If this doesn't work, then the problem might be the data in your array, data.

score 0 · Answer 2 · answered Dec 27 '22 at 21:46

You have the line char *check = strtok(data[line],d);. You've not shown what d is, but unless it is a string with no characters in common with the input line, strtok() just mangled your stored data, zapping whatever is the first character from d with a null byte. That means your sscanf() will fail because it isn't looking at the whole line. If, perchance, you have const char d[] = "\r\n"; or equivalent, this ceases to be relevant, beyond pointing out that you should show enough code to reproduce the problem.

Question about reading int and String from array

2 Answers2