Телеграмм чат группы supapro страница 38212

ага - особенно конкатенация строк очень быстро кучу в решето превращает:
Running out of heap is the most common cause for crashes. Because the build process for the ESP leaves out exceptions (they use memory), memory allocations that fail will do so silently. A typical example is when setting or concatenating a large String. If allocation has failed internally, then the internal string copy can corrupt data, and the ESP will crash.

In addition, doing many String concatenations in sequence, e.g.: using operator+() multiple times, will cause memory fragmentation. When that happens, allocations may silently fail even though there is enough total heap available. The reason for the failure is that an allocation requires finding a single free memory block that is large enough for the size being requested. A sequence of String concatenations causes many allocations/deallocations/reallocations, which makes “holes” in the memory map. After many such operations, it can happen that all available holes are too small to comply with the requested size, even though the sum of all holes is greater than the requested size.

So why do these silent failures exist? On the one hand, there are specific interfaces that must be adhered to. For example, the String object methods don’t allow for error handling at the user application level (i.e.: no old-school error returns). On the other hand, some libraries don’t have the allocation code accessible for modification. For example, std::vector is available for use. The standard implementations rely on exceptions for error handling, which is not available for the ESP, and in any case there is no access to the underlying code.

источник

19:05пожаловаться #8

s

std::slavik in supapro.cxx

но у esp проблема еще в том что там сетевой стек крутится и чего он там выделяет когда не угадаешь

источник

19:06пожаловаться #9

C

CodeDetector in supapro.cxx

std::slavik

ага - особенно конкатенация строк очень быстро кучу в решето превращает:
Running out of heap is the most common cause for crashes. Because the build process for the ESP leaves out exceptions (they use memory), memory allocations that fail will do so silently. A typical example is when setting or concatenating a large String. If allocation has failed internally, then the internal string copy can corrupt data, and the ESP will crash.

In addition, doing many String concatenations in sequence, e.g.: using operator+() multiple times, will cause memory fragmentation. When that happens, allocations may silently fail even though there is enough total heap available. The reason for the failure is that an allocation requires finding a single free memory block that is large enough for the size being requested. A sequence of String concatenations causes many allocations/deallocations/reallocations, which makes “holes” in the memory map. After many such operations, it can happen that all available holes are too small to comply with the requested size, even though the sum of all holes is greater than the requested size.

So why do these silent failures exist? On the one hand, there are specific interfaces that must be adhered to. For example, the String object methods don’t allow for error handling at the user application level (i.e.: no old-school error returns). On the other hand, some libraries don’t have the allocation code accessible for modification. For example, std::vector is available for use. The standard implementations rely on exceptions for error handling, which is not available for the ESP, and in any case there is no access to the underlying code.

Всё ещё неправильно :( Оберните код в теги: 3 символа ` до и после кода (в случае одиночной конструкции достаточно 1 ` с обеих сторон). Спасибо!

источник

19:12пожаловаться #10

ВШ

Виталий Шанин... in supapro.cxx

Народ привет, только изучаю Си, подскажите где торможу, почему avr не считает остатки?

источник

19:13пожаловаться #11

ВШ

Виталий Шанин... in supapro.cxx

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 5

int main()
{
    int x[N], i, sum;
    float avr;
    srand (time(NULL));
    for (i=0; i<N; i++)
    {
        x[i] = rand()%10;
        printf("%d\n", x[i]);
    }
    for(i=0; i<N; i++)
    {
        sum+=x[i];
    }
    avr = sum/N;
    printf("sum = %d, avr = %f", sum, avr);
    return 0;
}

источник

19:13пожаловаться #12

C

CodeDetector in supapro.cxx

Виталий Шанин

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 5

int main()
{
    int x[N], i, sum;
    float avr;
    srand (time(NULL));
    for (i=0; i<N; i++)
    {
        x[i] = rand()%10;
        printf("%d\n", x[i]);
    }
    for(i=0; i<N; i++)
    {
        sum+=x[i];
    }
    avr = sum/N;
    printf("sum = %d, avr = %f", sum, avr);
    return 0;
}

Оберните код в теги: 3 символа ` до и после кода (в случае одиночной конструкции достаточно 1 ` с обеих сторон). Спасибо!

источник

19:13пожаловаться #13

s

std::slavik in supapro.cxx

Виталий Шанин

Народ привет, только изучаю Си, подскажите где торможу, почему avr не считает остатки?

потому что он считает sum/N?

источник

19:15пожаловаться #14

s

std::slavik in supapro.cxx

выглядит как average

источник

19:15пожаловаться #15

VV

Vadim Voitenko in supapro.cxx

Виталий Шанин

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 5

int main()
{
    int x[N], i, sum;
    float avr;
    srand (time(NULL));
    for (i=0; i<N; i++)
    {
        x[i] = rand()%10;
        printf("%d\n", x[i]);
    }
    for(i=0; i<N; i++)
    {
        sum+=x[i];
    }
    avr = sum/N;
    printf("sum = %d, avr = %f", sum, avr);
    return 0;
}