Revision as of 21:49, 30 April 2011

Lecture 1:

Lecture 2:

Lecture (1-26-2011):

1. include <stdio.h>

File *fhd;
int numRow=0;
int numCol=0;
int col = 0;
int ch;

if (arg<2)
{
     /*error*/
}

fhd = fopen(argv[1]."r");
if(fhd==0)
{
    /*error*/
}
   while(!feof(fhd))
   {
       ch = fgetc(fhd);
       if(ch=='\n')
       {
          numRow++;
        }
        if(num Col<col)
        {
           numCol = col;
            col = 0;
         }
          col++;
      }
printf("width=%d,height=%d\n",numCol,numRow);

gcc prog.c -o prog

We need to know the enviornment and the direction we are going to take:
Need to have a way to remember where we are located:

Pointers:
int x;
x=5

Value ---> 800
address 650y

int *y;
/* y is a pointer to integer*/
y = 'x'; <-- warning message
take x's addr

• y = LHS left hand side take y's value as an adr, modify the value at that addr.

= *y Right hand side (RHS) ---> Means assign
Take y's value as an addr, read from that addr.

• y = 50;
  y = &z;
  *y = 35; ---> z = 35

Goo mainstreet ---> address
family Johnson ----> value

int a[10];
^-- 3
if(ch=='A')
^-- 65 ascII

memory
one - dimension array
int *a;
a = malloc(numElem *sizeof(int));
^---a's value is the start addr of a piece of memory
a[0] = ____
x = a [0];
.
.
.
free(a); <--- lose 50 points RELEASE THE MEMORY (Memory Leak if not there)

Stack Heap
a 1000

C does not specify sizeof(int)
Portable: Run on different machine

malloc(#elem*sizeof(one elem));
^--- modify the value at that addr

if(a==0)
{
/* malloc fails */
//if malloc fails a is 0
}

you already know the size of the maze.

int array[numRow]; The program does not know when you compile the program!