Buffer lenght

[AlfaRomeo]

Hello, I´m trying to make a program to display some variables of Temperature and voltage stored inside 3 folders in ENV:

All is ok but I don´t know why some garbage square chars appear after the printed variables as could be seen from the image attached.

I even printed the lenght of the variables buffer in another window but it´s normal, without the size of the garbage squares that I don´t know where they come from

Does someone know how I can get rid of that garbage chars??

#include <proto/all.h>
#include <exec/types.h>
#include <intuition/intuition.h>
#include <libraries/dos.h>
#include <stdlib.h>
#include <stdio.h>

#define screenWidth 320
#define screenHeight 200
#define screenLeft 0
#define screenTop 0

// Recebe os files com as variaveis, abre-os, extrai e envia as variaveis
char *readFile(const char *envName)
{
    struct FILE *file;
    char fileName[100];
    char *buffer = NULL;
    size_t length = 0;
    size_t bytesRead;

    //Abre SensorFile para ler variavel
    sprintf(fileName,"ENV:%s",envName);

    file=fopen(fileName,"r");
    if(file==NULL){
        perror("Nao consegui abrir a variavel");
        return -1;
        }

    // Determina o tamanho do arquivo
    fseek(file, 0, SEEK_END);
    length = ftell(file);
    fseek(file, 0, SEEK_SET);
    printf ("Lenght: %i\n",length);
    // Aloca memória para o buffer
    buffer = (char *)malloc(length + 1); // +1 para o caractere nulo de terminação

    // Passa o conteúdo do arquivo para o buffer
    bytesRead = fread(buffer, 1, length, file);

    // Adiciona caracter nulo de terminação no final do buffer
    buffer[bytesRead] = '\0';

    fclose(file);
    return buffer;
    }

int main() {
   struct Window *myWindow;
   int hasEnded = FALSE;
   struct IntuiMessage *msg;
   ULONG msgClass;
   char *str;
   int i;

   char *varName[]={
   "AK_5V_supply_V",
   "AK_Internal_temp_C",
   "AK_RTC_battery_percent"
   };


   // open window on the public workbench screen
   struct NewWindow winlayout = {
      screenLeft, screenTop,
      screenWidth, screenHeight,
      0,1,
      IDCMP_CLOSEWINDOW,
      WFLG_SIZEGADGET | WFLG_DRAGBAR | WFLG_DEPTHGADGET | WFLG_CLOSEGADGET | WFLG_ACTIVATE,
      //NULL,
      //NULL,
      NULL, NULL,
      "Volts / Temp",
      //NULL,
      NULL,NULL,
      0,0,
      600,400,
      WBENCHSCREEN
   };
   myWindow = OpenWindow(&winlayout);
   i=0;
   while(i<3){
       str=readFile(varName[i]);       
       if(i==0){
           Move(myWindow->RPort, 40, 60);
           Text(myWindow->RPort, str, 5);
           }
       if(i==1){
           Move(myWindow->RPort, 40, 80);
           Text(myWindow->RPort, str, 10);
           }
       if(i==2){
           Move(myWindow->RPort, 40, 100);
           Text(myWindow->RPort, str, 14);
           }
   i++;
   }

   while (hasEnded == FALSE) {
       // wait for and event
       Wait(1L << myWindow->UserPort->mp_SigBit);

       // get message
       msg = GT_GetIMsg(myWindow->UserPort);

       // get class of message;
       msgClass = msg->Class;

       // handle message (close it);
       GT_ReplyIMsg(msg);

       if (msgClass == IDCMP_CLOSEWINDOW) {
           CloseWindow(myWindow);
           free(str);
           hasEnded = TRUE;
       }
   }
   return(0);
}

[a/b]

You're telling gfxlib to print 5/10/14 chars while the actual strings are shorter. You should do strlen() or something similar, and then send that to Text() as the 3rd parameter (length).

[AlfaRomeo]

Thanks a/b, already solved with "Text(myWindow->RPort, str, strlen(str)); "

[Photon]

If you have lots of strings, some library functions that require the length provided can be a nuisance.

The problem is the same as on any system, though. There are two solutions:
1. Store strings as BCPL, Pascal, etc together with a length value, e.g. before the first character of the string. This value is read when printing and updated when the string is manipulated to change its length. Low performance cost.
2. Put a termination character after the string, e.g. 0 (ASCIIZ). Requires scanning the entire string before even printing it, but allows free manipulation. High performance cost.

In C, a char array is zero-terminated, i.e. strlen() is category 2 / high performance cost.

[Karlos]

Originally Posted by Photon

If you have lots of strings, some library functions that require the length provided can be a nuisance.

The problem is the same as on any system, though. There are two solutions:
1. Store strings as BCPL, Pascal, etc together with a length value, e.g. before the first character of the string. This value is read when printing and updated when the string is manipulated to change its length. Low performance cost.
2. Put a termination character after the string, e.g. 0 (ASCIIZ). Requires scanning the entire string before even printing it, but allows free manipulation. High performance cost.

In C, a char array is zero-terminated, i.e. strlen() is category 2 / high performance cost.

You can do both if you are prepared to create your own type and only allow it to be modified by functions. That way you only need to strlen() it when any function you provide that can change it is called (you might even get away with checking the base address hasn't changed, but that seems risky since depending on how the string changes, it might remain in the same location).

[a/b]

Nah, keep it simple and just include STL's basic_string<template <template <template werwer, fsdfsd>, template <we,msdfsdf>, template <fesdfsdf> > >, template^25 <have, fun, with, 10, pages of, error, messages> >.