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cheroky's questions

Martin Hope
cheroky
Asked: 2020-06-01 06:54:07 +0800 CST
  • 3

Hello, I know that both perform type deduction, but what is the difference between the two? When is it more convenient to use decltypeenvelope autoand vice versa?

c++
Martin Hope
cheroky
Asked: 2020-05-29 08:07:06 +0800 CST
  • 11

Well, I am very interested in learning about this apparently useful new feature, but it is difficult for me because all the quality information available is in English. In the same way I try to learn but my English is not so good that I can only understand a few things. That is why I am asking here if someone could explain what the semantics of movement are and the details that go with it.

c++
Martin Hope
cheroky
Asked: 2020-05-12 06:09:15 +0800 CST
  • 0

What I have to do is store a randomly selected pair of characters in a matrix and print it like this.

? # ¡ x
x ? # ¡
0 - + *
+ 0 - *

The problem is that I can't find a way to mark the characters that have come out twice, so as not to include them anymore.

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

char a[4][4];
char cartas[]={'#','%','@','0','*','!','<','x'};
int total=sizeof(cartas);

int main()
{
   srand(time(0));

   for (int i=0;i<4;i++)
   {
       for (int j=0;j<4;j++)
       {
           a[i][j]=cartas[rand()%total];
           printf("\t%c",a[i][j]);
       }
     printf("\n\n");
   }
}

Does anyone know of a way?

c
Martin Hope
cheroky
Asked: 2020-04-27 12:07:26 +0800 CST
  • 5

I have seen articles in English that talk about this, as far as I can understand they are used for encapsulation in C. Can someone explain what exactly is an incomplete type and an opaque pointer? And what uses do they have in C?

c
Martin Hope
cheroky
Asked: 2020-11-02 06:33:35 +0800 CST
  • 0

Can someone explain why interpreting a float as an integer as I understand data would be lost, is it a valid C casting?

float sqrt7(float x)
{
   unsigned int i = *(unsigned int*) &x;
   i  += 127 << 23;
   i >>= 1; 
   return *(float*) &i;
}

In addition, after it is cast again to float, it is the first time that I see this type of code

c
Martin Hope
cheroky
Asked: 2020-10-25 18:59:50 +0800 CST
  • 10

Since in C/C++ floating-point literals without a suffix default to type double , then assigning such a literal to a float performs an implicit conversion from double to float .

float n = 3.14;

if(n == 3.14f)
   puts("Igual");

This does not print the message instead if we add the suffix f to 3.14 in the declaration of n to prevent the conversion if printed. The question is, is there a loss of precision when the conversion is carried out?

c
Martin Hope
cheroky
Asked: 2020-10-20 18:20:52 +0800 CST
  • 0

To check if it is possible I did the following:

try
{
    int *x = 0;
    *x = 1234;
}
catch(...)
{
    cout << "OK";
}

But when I run it, I still get a segfault. I've read on some sites that try/catch can't catch a segfault, but I don't know if that's true, could someone please confirm that for me.

c++