c - CS50 PSET4 pointers -


i attempting cs50 pset4.
can explain why first works instead of second?

essentially did was, declare char* colour outside loop in first , declared char* color inside of if statements in second.

this worked when declared char* outside of if statements

 void initbricks(gwindow window)  {     char* colour;     // todo     for(int i=0,y=20;i < rows; i++)     {          y+= 30;        for(int j=0,x=5,c=0;j < cols; j++)       {         if(i==0)         colour = "red";          if(i==1)         colour = "blue";          if(i==2)         colour = "cyan";          if(i==3)         colour ="orange";          if(i==4)         colour = "gray";          grect brick = newgrect(x,y,30,15);         setfilled(brick,true);         setcolor(brick, colour);         add(window, brick);                x+= 40;                }    }    }

but didn't work, when declared char* inside if statements 

void initbricks(gwindow window) {     // todo     for(int i=0,y=20;i < rows; i++)     {          y+= 30;        for(int j=0,x=5,c=0;j < cols; j++)       {         if(i==0)         char *colour = "red";          if(i==1)         char *colour = "blue";          if(i==2)         char *colour = "cyan";          if(i==3)         char *colour ="orange";          if(i==4)         char *colour = "gray";          grect brick = newgrect(x,y,30,15);         setfilled(brick,true);         setcolor(brick, colour);         add(window, brick);                x+= 40;              }    }    }

i new pointers far sort of understand char* sort of equivalent of string points address of variable, colour, in case.

however, not sure why don't have put in '&' (reference operator) when use in setcolor(brick, colour).

to see why second group of code doesn't work may helpful see as:

    if (i==0) {         char *colour = "red";     }      if (i==1) {         char *colour = "blue";     }

you can see more declaration of colour extends end of block, colour no longer exists when next statement executed.

as second question, setcolor using value of colour, (which pointer) no need pass reference it. setcolor can access string without reference.


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