How to Assign Multiple Values into a Struct at Once

how to assign multiple values into a struct at once?

The first is an aggregate initializer - you can read up on those and tagged initializers at this solution:

What is tagged structure initialization syntax?

It is a special initialization syntax, and you can't do something similar after initialization of your struct. What you can do is provide a member (or non-member) function to take your series of values as parameters which you then assign within the member function - that would allow you to accomplish this after the structure is initialized in a way that is equally concise (after you've written the function the first time of course!)

How to assign the same value to multiple members in a struct in C

One way would be

image[i][j].rgbtBlue = image[i][j].rgbtGreen = image[i][j].rgbtRed = average;

If you're getting tired of typing "image[i][j]", and you're doing a lot with it in the same stretch of code, you could set up a temporary variable:

RGBTRIPLE *trip = &image[i][j];

trip->rgbtBlue = trip->rgbtGreen = trip->rgbtRed = average;

Setting up a temporary variable like this has some pros and cons:

• Pro: it saves typing
• Con: but saving typing isn't really a goal, you only type it once
• Pro: it can be easier to read
• Con: if you're not careful (if i or j changes when you don't expect), it can introduce bugs

How to set value of all structure members at once?

Structs can be assigned to with the = operator, exactly the same way as any other value in C:

obj[0] = existing_test;
obj[1] = function_returning_test();

The above rely on struct values that have themselves come from somewhere else in the program (possibly having been initialized in multiple statements like in the question); to create a struct value in a single expression, use the object literal syntax:

obj[0] = (test){ .x = 15, .y = 17 };
obj[1] = (test){ .y = 19 };

Any fields left out of a such a literal are still present, but set to the appropriate zero value for their type, so in the above example obj[1].x is set to zero.

How to update multiple fields of a struct simultaneously?

Since your type is standard-layout, I think the only legal way to do this, as per the C++ standard, is with a union that contains sub-objects with custom operator= definitions.

With a union, you're allowed to view the common-initial sequence of the active member, provided all types are standard-layout types. So if we carefully craft an object that shares the same common members (e.g. 3 float objects in the same order), then we can "swizzle" between them without violating strict-aliasing.

For us to accomplish this, we will need to create a bunch of members that all have the same data in the same order, in standard-layout type.

As a simple example, lets create a basic proxy type:

template <int...Idx>
class Vector3Proxy
{
public:

    // ...

    template <int...UIdx, 
              typename = std::enable_if_t<(sizeof...(Idx)==sizeof...(UIdx))>>
    auto operator=(const Vector3Proxy<UIdx...>& other) -> Vector3Proxy&
    {
        ((m_data[Idx] = other.m_data[UIdx]),...);
        return (*this);
    }

    auto operator=(float x) -> Vector3Proxy&
    {
        ((m_data[Idx] = x),...);
        return (*this);
    }

    // ...

private:

    float m_data[3];
    template <int...> friend class Vector3Proxy;
};

In this example, not all members of m_data are used -- but they exist so that the "common-initial sequence" requirement is satisfied, which will allow us to view it through other standard-layout types within the union.

This can be built up as much as you need; float conversion for single-component operators, support for arithmetic, etc.

With a type like this, we can now build a Vector3 objects out of these proxy types

struct Vector3
{
    union {
        float _storage[3]; // for easy initialization
        Vector3Proxy<0> x;
        Vector3Proxy<1> y;
        Vector3Proxy<2> z;
        Vector3Proxy<0,1> xy;
        Vector3Proxy<1,2> yz;
        Vector3Proxy<0,2> xz;
        // ...
    };
};

Then the type can easily be used to assign to multiple values at once:

Vector3 x = {1,2,3};

x.xy = 5;

Or to assign components of one part to another:

Vector3 a = {1,2,3};
Vector3 b = {4,5,6};

a.xy = b.yz; // produces {5,6,3}

Live Example

This solution also ensures that sizeof(Vector3) does not change, since all proxy objects are the same size.

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Note: It's not valid in C++ to use a union with anonymous structs, though some compilers support it. So although it might be tempting to rewrite this like:

union {
    struct {
        float x;
        float y;
        float z;
    }; // invalid, since this is anonymous
    struct {
        ...
    } xy;
}

This is not valid in standard C++, and would not be a portable solution.

Assign multiple values of the structure in C#

Yes.

User bill = new User{
  ID = 1,
  name = "Bill",
  isAlive = false
};

How to add multiple values for a struct in c using pointer?

You cannot assign to an array, but you can assign to a struct, which contains an array:

p[0] = (paciens) { .name = "Test", .born_in = 1992};

will do this. This is called a compound literal.

https://ideone.com/f99rUF

Also note that you forgot to #include <stdlib.h> for malloc.

Assign Multiple Values To Multiple Data Structures

I'll give you two answers as intuition tells me you're probably better suited with an interface in this case:

With the given class:

export class WeatherData {    date: string;    city: string;    country: string;    temperature: number;    minTemperature: number;    maxTemperature: number;    weather: any;    weatherIcon: any;    // set up a constructor:    constructor(props?: Partial<WeatherData>) {      // take an optional object containing properties of weather data and assign it      Object.assign(this, props);    }}
// Setup for clarity sakeconst temperatures[] = //....const countries[] = //....// more arrays as given...
let weatherDataObjects: WeatherData[] = [];// Assuming these arrays are all the same length:for (let i = 0; i < temperatures.length; i++) {  weatherDataObjects.push(new WeatherData({    temperature: temperatures[i],    country: countries[i],    // ... assign the rest  }));}

Using a struct to pass multiple values

Wrap the third party library:

namespace david {

void need_2xcha_2xint(const Value_Holder& value) {
    ::need_2xcha_2xint(value.a, value.b, value.x, value.y);
}

}

Using it:

int main() {
    Value_Holder value;

    using david::need_2xcha_2xint;
    need_2xcha_2xint(value);
    return 0;
}

edit

I'm pretty sure you could encapsulate this using templates and function pointers.

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