Issue with printing 2D array of structs with "\n"

Question

I'm trying to print a 2D array of structs using printf in a box formation. Each struct holds an int and char value. When I try to print them it prints the int value just fine, but instead of printing the char value it prints �. When I remove the printf statement telling them to go to a new line after the second for loop(printf("\n")) finishes it prints just fine(except for the fact that it's not in a box formation. Is this some weird quark of C or am I overlooking something?

for(int i = 0; i < States-1; i++){
    for(int j = 0; j < 11; j++){
        printf("%d%c  ", mArray[i][j].state, mArray[i][j].action);
    }
    printf("\n");
}

The output looks like this:

99�  99�  99�  99�  99�  99�  99�  99�  99�  99�  99�  
99�  99�  99�  99�  99�  99�  99�  99�  99�  99�  99�  
99�  99�  99�  99�  99�  99�  99�  99�  99�  99�  99�  
99�  99�  99�  99�  99�  99�  99�  99�  99�  99�  99�

Here is the rest of my code:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "classes.h"

void corUsage(argc)
{
        if(argc == 1)
        {
                printf("usage: ./tokenize tm_file\n");
                exit(1);
        }

}

int curState = 0;
char curAction = 0;

void maketok(char *str)
{

        char *ptr = str;
        ptr = strtok(str, "/");
        curState = atoi(ptr);
        ptr = strtok(NULL, " ");
        curAction = ptr;
//      printf("%d / %s",curState, curAction);
}

struct Matrix
{
{
        int state;
        char action;
};

int main(int argc, char *argv[])
{
    corUsage(argc);

    //opens the file given(argc[1])
    FILE *fp;
    fp = fopen(argv[1], "r");

    //checks for errors
    if(fp == NULL)
    {//error occured
            perror(argv[1]);
            exit(1);
    }
    char buffer[256];//a buffer that holds stuff

    char *ptr = buffer;//a pointer to the buffer
    char *ptr2;//a pointer for MISC.

    int States;//The number of states
    int Start;//The starting state
    int Accept;//The ending state


    //this reads the first three lines of the tm.x file and stores
    //it in the variable above.
    ptr = fgets(buffer, 256, fp);
    ptr2 = strtok(ptr, " ");
    ptr2 = strtok(NULL, " ");
    States = atoi(ptr2);
    ptr = fgets(buffer, 256, fp);
    ptr2 = strtok(ptr, " ");
    ptr2 = strtok(NULL, " ");
    Start = atoi(ptr2);
    ptr = fgets(buffer, 256, fp);
    ptr2 = strtok(ptr, " ");
    ptr2 = strtok(NULL, " ");
    Accept = atoi(ptr2);

    struct Matrix mArray[States][12];//a 2D array that will be holding structs

    while((ptr = fgets(buffer, 256, fp)) != NULL)
    {
            char *cur = strtok(ptr, " ");
            int idx = atoi(cur);
            char *buffer2[256];//a buffer for MISC data
            int co = 0;//counter vairable that tells how many things are in the line.
            for(cur = strtok(NULL, " "); cur != NULL; cur = strtok(NULL, " "))
            {
                    buffer2[co] = cur;//possibily not co as index?
                    co++;
            }
            for(int q = 0; q < 12; q++)
            {
                    struct Matrix var;
                    var.state = 99;
                    var.action = "d";
                    mArray[idx][q] = var;
            }
            /*for(int i = 0; i < co; i++)
            {

                            maketok(buffer2[i]);
                            printf("%d / %s", curState, curAction);
                            mArray[idx][i].state = curState;
                            mArray[idx][i].action = curAction;

            }*/

            for(int i = 0; i < States-1; i++){
                    for(int j = 0; j < 11; j++){
                            printf("%d%c  ", mArray[i][j].state, mArray[i][j].action);
                    }
                    printf("\n");
            }

}

File that I'm reading in:

states 10
start  0
accept 9
0  0/0d  1/0d  2/1s  3/3s  4/2s  5/2s  6/5s  7/4s  8/4s  10/9d
1  0/9d  1/9d  2/1s  3/1s  4/1s  5/1s  10/9d
2  0/9d  1/9d  3/2s  4/2s  5/2s  10/9d
3  0/9d  1/9d  3/3s  4/3s  5/9d  10/9d
4  0/9d  1/9d  10/9d
5  0/9d  1/9d  7/6s  10/9d
6  0/6s  1/6s  2/6s  3/6s  4/6s  5/6s  6/6s  7/7s  8/6s  9/6s  10/9d
7  0/6s  1/6s  2/6s  3/6s  4/6s  5/6s  6/8s  7/7s  8/6s  9/6s  10/9d
8  0/9d  1/9d  10/9d

Please post complete code along with the variation of print loop you talked of. — user2776601
So I figured out that if I replace the print("\n") with gets("") it fixes the problem, but I still don't know why it does this. — Saint
Replacing a printf() (presumably) with a gets() and a constant string argument seems more likely to cause trouble than cure it. Your question would be more convincing if the code were compilable: struct Matrix { { int state; … is not valid C. — Jonathan Leffler

Saint Saint · Accepted Answer · 2014-10-11T22:37:44

Ok, so I figured it out.

in this loop:

for(int q = 0; q < 12; q++)
        {
                struct Matrix var;
                var.state = 99;
                var.action = "d";
                mArray[idx][q] = var;
        }

I declare var.action = "d";. It should be var.action = 'd'; in single quotes only.

Thank you to anyone who took the time to look at this.

Issue with printing 2D array of structs with "\n"

1 Answers