Could anyone suggest a good title to learn how works SDL library, not SDL2 I meant

Could anyone suggest a good title to learn how works SDL library, not SDL2 I meant

Use SDL2

But could i use it for C programming, and not just C++?

Could anyone suggest a good title to learn how works SDL library, not SDL2 I meant

Ha my bad, okay thanks you

@Elkira01 Deleted your old messages by mistake while clearing some other spam. Apologies.

Hey,,,someone to help me,,,,, int n; cout << "Enter an integer: "; cin >> n; if (n < 10) cout << "less than 10" << endl; else if (n > 5) cout << "greater than 5" << endl; else cout << "not interesting" << endl; what values of n would cause the output to be "not interesting"

this your homework?

Yeah,,i tried a lot but still don't get the values

did you try reading the code?

Hey,,,someone to help me,,,,, int n; cout << "Enter an integer: "; cin >> n; if (n < 10) cout << "less than 10" << endl; else if (n > 5) cout << "greater than 5" << endl; else cout << "not interesting" << endl; what values of n would cause the output to be "not interesting"

Hey,,,someone to help me,,,,, int n; cout << "Enter an integer: "; cin >> n; if (n < 10) cout << "less than 10" << endl; else if (n > 5) cout << "greater than 5" << endl; else cout << "not interesting" << endl; what values of n would cause the output to be "not interesting"

none. a good compiler will not even generate code for that branch, a good linter will tell you that the else part is never reached and ask you to remove the code.

Good compiler like which one bro

Hey there! I'm getting this message: "make: Nothing to be done for 'substitution'." while trying to compile this: #include <ctype.h> #include <cs50.h> #include <stdio.h> #include <string.h> #include <math.h> int main(int argc, string argv[]) { if(argc != 2) { printf("Usage: ./substitution key.\n"); } if(strlen(argv[1]) != 26) { printf("Key must contain 26 characters.\n"); } for(int i = 0; i < strlen(argv[1]); i++) { for(int n = i+1; n < strlen(argv[1]) + 1; n++) { if(isalpha(argv[1][i]) && tolower(argv[1][i]) == toupper(argv[1][n])) { //fine } } } } It was compiling yesterday just fine

gcc, clang, msvc

What is the better condition to check whether a given interger is a prime number or not,,,,,,,

#QuestionForBeginners Why were references added to C++ when you could do everything that a reference could do using pointers?

i could never understand the meaning of references tbh

#QuestionForBeginners Why were references added to C++ when you could do everything that a reference could do using pointers?

After working with golang for some time I can say references is a bliss. Compared to having to check every pointer for being null, or crashing here and there

Let say we define a string variable in cpp, string s("Hello World!"); than what is the difference between 1. s.c_str(); 2. (char*)s.c_str();

Hello. I have chosen the topic "pointer" for my project. Now i have to make and show a program and i'm unable to think for a c++ program which can implement pointers. Any recommendations? Also the program should'n be too easy or too hard. I'm in second sem.

nevertheless sorting algorithms or small games are nice point to start from

selection sort then maybe

Ah! nice you mean replace array with pointer 👀

declare an array of random integers in your main, then make a void function that takes a pointer to this array and sorts it

or declare the array in the another function that returns a pointer

return a pointer to a local array?

#QuestionForBeginners Why were references added to C++ when you could do everything that a reference could do using pointers?

#QuestionForBeginners Why were references added to C++ when you could do everything that a reference could do using pointers?

#QuestionForBeginners Why were references added to C++ when you could do everything that a reference could do using pointers?

I read through all the reasons here. Most of them were about references being safer because they have to refer to an object and that we dont have to check for null references. Though true, we yet still do read so many gotchas about returning references to local objects. So it is not like references address the problem of null pointers or invalid pointers completely. The other reasons mentioned were that references once initialized cannot be made to point to another variable. Well constant pointers can be used for the same thing. Infact references are implemented using constant pointers most often. Actually the reason why references were introduced was none of these. They were actually proposed by Alexander Stepanov and the reason why he wanted them to be added to C++ was to support operator overloading. References make using operators analogous to how we use them on built in types because they are just aliases (as mentioned by Aman). Let us take the assignment operator for example. Assignment operator on built in types returns a reference to its left hand side operand. So if we were to overload the assignment operator for our class, we would do something like this: class A { public: A& operator=(const A&); }; This allows us to do A obj, obj1, obj2; (obj = obj1)=obj2; If it were not for references, we would have to do something like class A{ public: A* operator=(const A* const); }; To use it like how we did earlier, we would have to do something like A obj, obj1, obj2; *(obj=&obj1)=&obj2; The same applies to all other operators as well. References being just aliases allows us to use them for operator overloading making it easier for the clients to call them just like they would do using variables of built in types. (From the Annotated C++ Reference Manual)

Good to know it. Thanks. There is a few moment I began to learn operator overloading; and I haven't digested it yet 😩. But I noticed that the structure of some operators was a bit different(doesn't return a reference to its left hand operand?). For example: *, + and == Class B { public: B operator +(const B&) const; B operator *(const B&) const; bool operator == (const B&) const; } Client program: B b1, b2, b3, b4; b1 = b2 + b3; b4 = b1*b2; if(b1 == b2) do something; work as well (without using the ampersand symbol). May you clarify me here, please?

Only some expressions return a glvalue. For example assignment, dereferencing operator (*) and so on. The operators +(binary as well as as unary), *(binary), == all return rvalues when used with built in types like int etc (they return prvalues and for objects of class types in C++17 terms they should return either an xvalue or a prvalue). You can just assume rvalues as those values to which an rvalue reference can be bound. Each operator has a well defined meaning when applied to built in types as in like whether it returns a glvalue or a rvalue. When you overload these operators for your classes, you should ensure that the behavior of these operators is the same as when applied to built in types. The compiler wont enforce this. For example while overloading binary + operator, nothing prevents you from returning a pointer as a return value but clients of your code would be surprised by such behavior. To see when you should return a reference and when you should not, you can just use the built in meaning of these operators as an example and check it out. int a , b , c; (a = b) = c; //assigns c to a finally This compiles fine. This means that built in operator= returns a reference and so your overloaded operator= should return a reference as well. a*b = c; This fails to compile which means the built in binary * operator does not return a glvalue. Hence your overloaded operator should not either which is why you return a value rather than a reference when you overload this operator.

I have other question (not related to the first one). I have a simple code that read data stored in a file. It works well when I use Qt creator, but doesn't work when using codeblocks. Why? I changed nothing in the code

Do you use the same compiler? Same working directory?

Same compiler, not same directory All code are in main.cpp. I created on project for qt creator, one for codeblocks and in both cases I put the file containing the data(test.txt) in the same directory that exe file

Post your code on pastebin.com

https://pastebin.com/npstZdC7

This should work irrespective of the IDE as long as the input file "test.txt" is accessible. Just check ifstream status after the open call using inFile.is_open() to see if the file was opened successfully. Check the permissions on the input file as well to see if your program has read access to it. Also check if the program has write permission to the directory concerned.

I read through all the reasons here. Most of them were about references being safer because they have to refer to an object and that we dont have to check for null references. Though true, we yet still do read so many gotchas about returning references to local objects. So it is not like references address the problem of null pointers or invalid pointers completely. The other reasons mentioned were that references once initialized cannot be made to point to another variable. Well constant pointers can be used for the same thing. Infact references are implemented using constant pointers most often. Actually the reason why references were introduced was none of these. They were actually proposed by Alexander Stepanov and the reason why he wanted them to be added to C++ was to support operator overloading. References make using operators analogous to how we use them on built in types because they are just aliases (as mentioned by Aman). Let us take the assignment operator for example. Assignment operator on built in types returns a reference to its left hand side operand. So if we were to overload the assignment operator for our class, we would do something like this: class A { public: A& operator=(const A&); }; This allows us to do A obj, obj1, obj2; (obj = obj1)=obj2; If it were not for references, we would have to do something like class A{ public: A* operator=(const A* const); }; To use it like how we did earlier, we would have to do something like A obj, obj1, obj2; *(obj=&obj1)=&obj2; The same applies to all other operators as well. References being just aliases allows us to use them for operator overloading making it easier for the clients to call them just like they would do using variables of built in types. (From the Annotated C++ Reference Manual)

This message couldn't be displayed on your device due to copyright infringement.

you don't really need to specify what IDE you are using, the language stays the same

well, i don't know courses that are based on IDEs, sorry

Do you have any course for learning c++ nd data structure?

This should work irrespective of the IDE as long as the input file "test.txt" is accessible. Just check ifstream status after the open call using inFile.is_open() to see if the file was opened successfully. Check the permissions on the input file as well to see if your program has read access to it. Also check if the program has write permission to the directory concerned.

I checked, but nothing happened (the message checking didn't print). But when I did the same deleting test.txt in Qt creator, the checking message print something... And curiously I opened the ouput file generated by the compiler. We can see Student name, Test scores and average test score with garbage values.

Does anyone have an idea on how i could do this text formatting? Or is it just not exists? Image Link They produce link inside a text just like what Telegram did to my image link above

https://unix.stackexchange.com/questions/284476/terminal-create-hyperlinks#437581 it's hyperlink