Thread: looping problem?

hi, everyone!

please take a look at my program:

Code:

int main()
{
   while(1)
   {
     printf("\n>> ");
     gets(cmd_str);

     split_cmd();

     if( strcmp(cmd_wrds[0],"MAKE") == 0 ) make();
	 
   }
    return 0;
}

int make(void)
{
    char matrix_name;
    matrix_name=cmd_wrds[1][0];
    if (matrix_name == 'A') v=0;
    else if (matrix_name == 'B') v=1;
    else if (matrix_name == 'C') v=2;

        printf("Enter number of rows: ");
        scanf("%d",&row);
        printf("Enter number of columns: ");
        scanf("%d",&col);

	for (i=0;i<row;i++){
      for (j=0;j<col;j++){
           printf("%c[%d][%d] = ",matrix_name,i,j);
           scanf("%d",&m[v][i][j]);      }}  
    return 0;    
}

it does fine on first try but after the first looping of the code it does something unnecessary and i don't know why it does that.
it's like this:

Code:

>>MAKE A
Enter number of rows: 2
Enter number of columns: 2
A[0][0] = 1
A[0][1] = 2
A[1][0] = 3
A[1][1] = 4

>> //this is what i'm talking about, it should only show once before asking for another command
>>MAKE B

what seems to be the problem?
by the way, the program still works fine after the first loop, i think, it's just that ">>" that's bothering me. where did it came from?
thanks to those who'll help!

a) you're using gets() - very bad, read the FAQ
b) you're mixing scanf() with other input methods - not so good
c) lots of global variables - try using parameters.

> that's bothering me. where did it came from?
It's the \n left behind by the previous call to scanf

Using fgets() to read ALL input into a buffer, then using your parser (or sscanf or whatever) when it's in memory is a lot saner in the long run.

you call make()
make calls scanf()
You type in

1\n
2\n
3\n
4\n

scanf happily skips newlines by itself, but when you switch back to some other input method then surprises appear.

Use fgets() + sscanf() for ALL input.

gets is dangerous, read SourceForge.net: Gets - cpwiki.
scanf, as mentioned, will read your integral data and leave the newline. See SourceForge.net: Scanf woes - cpwiki.

For gets, works the same, yes, same syntax, no. Look up fgets in your favorite documentation.