incompatible types in assignment

**vapanchamukhi** · 09-18-2008

following is main function of my program

Code:

#include<stdio.h>
#include"header.h"

main()
{
    unsigned char crc;
    unsigned char ar;
    pdt pv;
    adt av;
    frame *f1;
    frame fr;
    
    int src1=0;
    int dest1=1;

    av.ack=9;
    
//opens a file and assigns a file descriptive to fp
    fp=fopen("txtfile","r");

   //generates stuffed information
   stuff(&pv,fp);
   
    //creates the control byte
    control_byte(&pv);

    //crc is generated for the information
    crc=crc_gent(&pv);

    //frame is created..
    f1=(frame *)make_frame(&pv,crc,src1,dest1);
    
    //push that frame into a buffer
    push(f1);
    
//check for the acknowledgement from the receiver side
    ar=ack_check(&av);

//sliding window is created...
    fr = slide(512,ar); //incompatibe type in assignment
}

my header file is

Code:

#include<stdio.h>
//typedef int frame_type;

FILE * fp;

typedef struct payload {
	int frm_typ;
	unsigned char cb;
	unsigned char stuf_info[5];
}pdt;

typedef struct frame {
	char st_flag;
	int src_addr;
	int dest_addr;
	pdt p;
	unsigned char crc;
	char end_flag;
}frame;
struct frame f4[512];

typedef struct ack_frme
{
char st_flg;
int src_addr;
int dest_addr;
unsigned char ack;
char end_flg;
}adt;

i have problem in
fr = slide(512, ar);

slide function is returning a frame..
but for that line its giving error as incompatible types in assignment.

**Salem** · 09-18-2008

So where is the prototype for slide() in all of that.

The make_frame() cast is almost certainly wrong for the same reason, except all that you've managed to do is stop the compiler from complaining about it.

**vapanchamukhi** · 09-18-2008

thats my main header file.... for each function one library is created and also a header file. in that the function prototypes are declared....

**Salem** · 09-18-2008

If slide() is defined in slide.c and prototyped in slide.h, then you also need
#include "slide.h"
in your main

**vapanchamukhi** · 09-18-2008

This is my slide function... i have taken 'f' as a variable of frame type. and slide function is returning this 'f' which is of frame type.... so in the main function also im receiving this in a variable which is also of type frame... so also it is giving error... im actually not understanding any thing why its giving error????

Code:

 #include<stdio.h>
 #include"header.h"

  int sequence(unsigned char seq);


frame slide(int size,unsigned char seq)    //for sliding window of size 5
 {
    int frameN;
    frame f;
    static int i=-1,j=-1,c=0;           /* i indicates the index of start of window and j indicates the index of last frame sent in the window, required the values of i and j to be static as to persist in the next function calls*/
	    int k;                                 //index of the frame to sent is remembered in k
    frameN=sequence(seq);
    if(c==5 && frameN==0)                            /* if no acknowledgement is received when window size is over then setting the values of i and j to                                                         retransmit frames*/
    {
      j=i;
      c=0;                                   //resetting window size counter to zero
    }
   else                  
       if(frameN==0)                       // if window counter is less than 5,and acknowledgement is not received then keep on sending frames        
       {
           c++;
           j++;
       }
    else                   //when acknowledgement is received the indices i and j are set according to the sequence no. mentioned in acknowledgement 
       {
	       i=j=frameN;
           c=0;
       }
        k=j;             // index of the frame to sent is remembered in k
        j++;             //as sendind of frame takes place, index j is increased by one
    f = f4[k];
    return f;
 }

**goldenhunter** · 09-19-2008

check your compiler version?

**tabstop** · 09-19-2008

I don't see a prototype of slide() in your header.h file -- and unprototyped functions return int.

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