how can input txt file to 2d array completely at C

Question

I'm trying to get txt file to 2d array. But some values at the back are missed. I wonder why this happening.

#define MAZE_ROW 11
#define MAZE_COL 22

char maze[MAZE_ROW][MAZE_COL];
int main(){
    Get_Maze();
    Print_Maze();
}

void Get_Maze(){
    FILE *f=fopen("maze.txt","r");
    for(int i=0;i<MAZE_ROW;i++){
        for(int j=0;j<MAZE_COL;j++){
                fscanf(f,"%c",&maze[i][j]);
        }
    }
    fclose(f);
}

void Print_Maze(){
    for(int i=0;i<MAZE_ROW;i++){
        for(int j=0;j<MAZE_COL;j++){
            printf("%c",maze[i][j]);
        }
    }
}

this is the result of my code

For our convenience, please add the content of the input txt file as well as the resulting output as a text-block instead of a linked image. This would allow easy copy+paste in order to reproduce the issue. — grek40
– grek40, Commented Apr 12, 2021 at 9:45
First, you need to declare your function before calling them. Second, why do you think something is missing? Have you counted the characters in the output? How many are there? — n. m. could be an AI
– n. m. could be an AI, Commented Apr 12, 2021 at 9:47
Actually, I think you read line break characters from the input txt into your array. Instead you need some way to skip them and only read the 0|1 content. — grek40
– grek40, Commented Apr 12, 2021 at 9:50
fscanf(f,"%c",&maze[i][j]); will read '\n' too. 황성문, is that what you want? Try "%c" --------> " %c" (add space). — chux
– chux, Commented Apr 12, 2021 at 9:54

kristofko · Accepted Answer · 2021-04-12 10:45:42Z

2

the problem is with the '\n' - newline characters. In your text file, at the end of every line, there is a '\n', and by using fscanf(f,"%c",&maze[i][j]);, you are not skipping any whitespaces (space, tab, newline character, etc) and thus your code skips the last few 0|1 in your text file, since some of its values are already assigned to '\n' and the maze[MAZE_ROW][MAZE_COL] variable has too few mebers.

A quick fix would be to use for example:

fscanf(f," %c",&maze[i][j]); (with space before %c) - this will cause fscanf to ignore any whitespaces, in your case the '\n', and it will only load the characters you wanted to.

Problem is that this will cause your output to be in a single line, since you are not printing any new line, so the last thing is to change your Print_Maze() to this

void Print_Maze(){
    for(int i=0;i<MAZE_ROW;i++){
        for(int j=0;j<MAZE_COL;j++){
            printf("%c",maze[i][j]);
        }
        printf("\n");
    }
}

answered Apr 12, 2021 at 10:45

kristofko

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2 Comments

stark Over a year ago

this will also skip spaces in the input file.

kristofko Over a year ago

Well, yes, but since his input file doesnt have any spaces, it won´t affect anything in the output. I specified it in my answer by saying that the only whitespace ignored in this case will be the '\n'

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