Why🙆🏿‍♀️

Error: main.c: In function ‘main’: main.c:26:41: error: ‘n’ undeclared (first use in this function) printf("factorial(5) = %d\n", factorial(n));  

N is not declared as a variable

Error: main.c: In function ‘main’: main.c:26:41: error: ‘n’ undeclared (first use in this function) printf("factorial(5) = %d\n", factorial(n));  

I declare it in function interface

n does not exist in the scope of main, just replace n with a number there

Why would you even want to scan into a param

Declare a variable Ask user for a value then make this variable receive it Then, on printf this value will be copied into the n of the function. That's how it works

Hi everyone, I started learning Qt and QML cause I'm developing a mobile application and I wanna use C++ for the logic of the app. Is there another way to do the GUI and still be using C++ for the logic? Is there another way to make my app cross-platform?

i know with qt you can use html and css to do the graphics

Hi everyone, I started learning Qt and QML cause I'm developing a mobile application and I wanna use C++ for the logic of the app. Is there another way to do the GUI and still be using C++ for the logic? Is there another way to make my app cross-platform?

Okay but is there an alternative to Qt?

Hi everyone, I started learning Qt and QML cause I'm developing a mobile application and I wanna use C++ for the logic of the app. Is there another way to do the GUI and still be using C++ for the logic? Is there another way to make my app cross-platform?

When should I use a function pointer?

When should I use a function pointer?

i.e it's a callback or you want to call a function depending on a condition that you cannot check right here and now

My code is throwing error

Here's my code Codeshare.io/5Nwblr

Today is catholic easter, bruh

Compile Error on line 25,30,33

Please can some help in arrays in c++ ????

#include<stdio.h> #include<stdlib.h> struct student { int marks; char name[30]; }; void main() { struct student *ptr; int n, i; printf("enter the no. of records"); scanf("%d%d", &n); ptr= (struct student *)malloc(n * sizeof(struct student )); for (i=0; i<n; i++){ printf("enter name and marks: \n"); scanf("%s%d",(ptr + i)->name,&(ptr + i)->marks); }

What is your problem with them?

what does last line (ptr + i) means

also &(ptr + i)

Taking pointer to an student element (as if it's in an"array" of size n, then you take an element on position i)

Compile Error on line 25,30,33

means it will store the data at array's ith position

Hi guys. Can anyone ask my question please? I watched a video about Arduino Uno project and I have Arduino uno R3 on Proteus. Are they same or not?

Yes Basically malloc allocated enough memory to store n elements of student. ptr points to the start of the "array" the pointer type is student, so if you add a number to this pointer, it will shift in memory on the size of student structure multiplied by the number you've added Effectively the same as addressing an array

but since there is no array declare in it then how the date will store in the array or ptr will work as array

Well, let's say your student structure takes 34 bytes of memory to be stored, you entered 3 as n. malloc will allocate 102 bytes and give you the pointer to the start of this memory. Then you iterate your loop, on the first iteration you add zero to this pointer. And interpret 34 bytes at the start as if it was a student struct. You read mark into 4 first bytes and name into next 30 bytes. Then you do the second iteration with i=1. You add one to the address and it shifts it by 34*1=34 bytes, right after memory of the first "student" ends. Then you do the same reading into the memory as if it was int and char[30]. And then do that the third time to fill the third student, memory of which will end exactly on 102nd byte. When you use arrays, they do the same math under the hood basically.

I want to learn c++.. I have no programming background..where should I start...

ok I got it but how the marks is store or mark is store to the address of ptr ?

mark is stored in the first bytes of the memory of the student structure. (ptr+i) points to the memory of the struct, (ptr+i)->marks gives you the value of marks of that struct, &(ptr+i)->marks gives pointer to that memory of the mark of that struct (that can be used to read to it by scsnf

mark is stored in the first bytes of the memory of the student structure. (ptr+i) points to the memory of the struct, (ptr+i)->marks gives you the value of marks of that struct, &(ptr+i)->marks gives pointer to that memory of the mark of that struct (that can be used to read to it by scsnf

@Rahul_4737 Same as ptr[i] or ptr[i]->marks.

thank you so much

This is not exactly correct cut from the code above &(ptr + i)->marks taking pointer of marks of this element