SDL C++ Jumping - c++

Question

const int jumpHeight = 10;
//Non-Const variables
bool running = true;
bool isJumping = false;
bool isFalling = false;
int jump = 0;
Uint8 *keystate = NULL;
//Structs
typedef struct entity {
SDL_Rect hitbox;
} playerType, enemyType;
playerType player;
enemyType basicEnemy[10];
//Main Function
int main( int argc, char* argv[] )
{
while( running )
{
keystate = SDL_GetKeyState(NULL);
if( keystate[SDLK_UP] )
{
if(isJumping != true)
{
isJumping = true;
}
}
if( keystate[SDLK_LEFT] ) player.hitbox.x -= 1;
if( keystate[SDLK_RIGHT] ) player.hitbox.y += 1;
//Window collision
if( player.hitbox.x < 0 ) {player.hitbox.x = 0;}
else if( player.hitbox.x > SCREEN_WIDTH - player.hitbox.w ) {player.hitbox.x = SCREEN_WIDTH - player.hitbox.w;}
if( player.hitbox.y < 0 ) {player.hitbox.y = 0;}
else if( player.hitbox.y > SCREEN_HEIGHT - player.hitbox.h ) {player.hitbox.y = SCREEN_HEIGHT - player.hitbox.h;}
//Jumping
if( isJumping == true )
{
if( jump >= jumpHeight || isFalling == true )
{
jump--;
player.hitbox.y--;
isFalling = true;
}else if( jump <= 0 && isFalling == true )
{
jump - 0;
isFalling = false;
isJumping = false;
}else {
jump++;
player.hitbox.y++;
}
}
}
}
This is my current code in my game (the parts related to jumping anyway). When I press the Up key my character goes to the top of the window and stays there. Where have I gone wrong?
I compile with g++ -o myprogram.exe mysource.cpp -lmingw32 -lSDLmain -lSDL -lSDL_image -static-libgcc -static-libstdc++.
Walking you through how the code is supposed to work:
Press Up: isJumping becomes true, and then the player is raised to the max height, then goes down again to where it started (later I will add collision checking)

Answer 1

He's going to the top of the window because of this code here:
if (jump >= jumpHeight || isFalling == true) {
jump--;
player.hitbox.y--;
isFalling = true;
}
Once this condition has been met, it will run for the rest of the loop and the conditions will never be false. To fix it, you need to check if jump is 0 after you decrement it. If it's 0, set isFalling to false and isJumping to false.
Also, do note that when you increase the y, you're making the unit go lower on the window because SDL windows have origins starting from the top left corner and the Y axis is downward.
Replace all increments of y with decrements and vice versa.