FString::FromInt, I don't know why there's a error message

Question

void ACountdown::UpdateTimerDisplay()
{
CountdownText->SetText(FString::FromInt(FMath::Max(CountdownTime, 0)));
}

And,

void ACountdown::CountdownHasFinished()
{
CountdownText->SetText(TEXT("Go!"));
}

This is an example of a countdown where the text 3, 2, 1 Go! is printed after the game starts. However...Error message were printed in the two parts above. (FString::FromInt and TEXT)

The error message is as follows.

Error (active) E0312 no suitable user-defined conversion from "FString" to "const FText" exists

Error (active) E0415 no suitable constructor exists to convert from "const wchar_t [4]" to "FText"

Error C2664 'void UTextRenderComponent::SetText(const FText &)': cannot convert argument 1 from 'FString' to 'const FText &'

Error C2664 'void UTextRenderComponent::SetText(const FText &)': cannot convert argument 1 from 'const wchar_t [4]' to 'const FText &'

I wrote the whole code at the bottom. I was following the example below. I practiced the examples of Variables, Timers, and Events below.
(https://docs.unrealengine.com/5.0/en-US/quick-start-guide-to-variables-timers-and-events-in-unreal-engine-cpp/)

Did I forget about the header file? I'm at Countdown.cpp

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "Components/TextRenderComponent.h"
#include "Countdown.generated.h"

at Countdown.h

#include "Components/TextRenderComponent.h"
#include "Countdown.h"

I'm just guessing there's something missing in the notation of the string. I rewrote the code more than five times because I'm afraid I made a mistake. But nothing has changed. Is there something that works on UE4 but not on UE5? How can I fix this?

Thank you for reading it.

it is Countdown.h

#pragma once

#include "CoreMinimal.h"
#include "GameFramework/Actor.h"
#include "Components/TextRenderComponent.h"
#include "Countdown.generated.h"

UCLASS()
class MYPROJECT_API ACountdown : public AActor
{
GENERATED_BODY()

public: 
ACountdown();

protected:
virtual void BeginPlay() override;

public: 

virtual void Tick(float DeltaTime) override;

int32 CountdownTime;

UTextRenderComponent* CountdownText;

void UpdateTimerDisplay();

void AdvanceTimer();

void CountdownHasFinished();

FTimerHandle CountdownTimerHandle;

};

and Countdown.cpp #pragma once

#include "Components/TextRenderComponent.h"
#include "Countdown.h"

ACountdown::ACountdown()
{
PrimaryActorTick.bCanEverTick = false;

CountdownText = CreateDefaultSubobject<UTextRenderComponent>(TEXT("CountdownNumber"));
CountdownText->SetHorizontalAlignment(EHTA_Center);
CountdownText->SetWorldSize(150.0f);
RootComponent = CountdownText;

CountdownTime = 3;
}

void ACountdown::BeginPlay()
{
Super::BeginPlay();

UpdateTimerDisplay();
GetWorldTimerManager().SetTimer(CountdownTimerHandle, this, &ACountdown::AdvanceTimer, 1.0f, true);
}

void ACountdown::UpdateTimerDisplay()
{
CountdownText->SetText(FString::FromInt(FMath::Max(CountdownTime, 0)));
}

void ACountdown::AdvanceTimer()
{
--CountdownTime;
UpdateTimerDisplay();

if (CountdownTime < 1)
{
GetWorldTimerManager().ClearTimer(CountdownTimerHandle);
CountdownHasFinished();
}
}

void ACountdown::CountdownHasFinished()
{
CountdownText->SetText(TEXT("Go!"));
}

Answer 1

I second what ken wrote: You are trying to pass an FString where an FText is required. But since you are coming from an int, you could use FText::AsNumber.

CountdownText->SetText(FText::AsNumber(FMath::Max(CountdownTime, 0)));

---

You should research the differences between the three types of text representation in unreal FName, FString and FText.

FName is internally a number in a lookup table, so you can copy it without actually copying a string. Also comparison is identical to just comparing two integers (because, that's what actually happens). There are some downsides: FName ignores whitespace and is case insensitive.

FString is your good old string, similar to std::string. It stores an array of char and an int denoting it's length. Comparing it is tedious and copying expensive. But it's flexible and can easily be extended.

FText is used for localization. Internally, it is similar to FName, consisting of a reference to a string somewhere else, but it is at the same time localization agnostic. It also provides formatting options that are also localization agnostic (e.g. gender and count related changes in sentences).

Now, UI always uses FText, because it makes it easy to swap strings between languages. Object identifiers are always FName, because it allows them to be uniquely identifiable. You have to know how to convert these three types of "strings" into each other, to use them effectively.

---

Note about the TEXT() macro: It is used to convert a platform const char* into a const wchar_t*, so essentially makes sure that the input is in the correct format that unreal uses to represent characters internally. You can use this, to make FString instances, because FString implicitly allows this. FText does not.

If you want to create an FText out of a string literal, you have two options:

1. Create localizable text. This can be done by using LOCTEXT() or NSLOCTEXT() based on if you have defined LOCTEXT_NAMESPACE in your file.
2. Create an invariant text using INVTEXT(). It's not used by the localizer, and is essentially a shorthand for FText::FromString(TEXT()). (It's not identical, but it feels identical to you as a programmer).

Answer 2

You're trying to set an FString instead of an FText, which you can't do. To set an FText, you use the TEXT macro or convert the FString with another method.

void ACountdown::UpdateTimerDisplay()
{
CountdownText->SetText(TEXT("%s"), FString::FromInt(FMath::Max(CountdownTime, 0)));
}