Euler and rk4

#include<stdio.h>
#include<stdlib.h>
float dydx(float x, float y)
{
    return((x - y)/(x+y));
}
int main()
{

    float k1, k2, k3, k4, k5;
    float x0 = 0, y0 = 1, x = 1.4, h = 0.2,y;

    int n; int ch;
    n = (int)((x - x0) / h);
    y = y0;
    while(1)
    {
    printf("\n\n1. Euler's method\n2. RK4\n3. Exit\n");
    scanf("%d",&ch);
    switch(ch)
    {
    case 1:
        x0 = 0, y0 = 1, x = 1.4, h = 0.2;
        y=y0;
        printf("\nx\ty");
        for(int i=1;i<=n;i++)
        {
            y=y+h*dydx(x0,y);
            x0=x0+h;
            printf("\n%.3f\t%.3f",x0,y);
        }
    break;
    case 2:
        x0 = 0, y0 = 1, x = 1.4, h = 0.2;

        y=y0;
    printf("\nx\ty");
    for (int i=1; i<=n; i++)
    {
        k1 = h*dydx(x0, y);
        k2 = h*dydx(x0 + 0.5*h, y + 0.5*k1);
        k3 = h*dydx(x0 + 0.5*h, y + 0.5*k2);
        k4 = h*dydx(x0 + h, y + k3);
        y = y + (1.0/6.0)*(k1 + 2*k2 + 2*k3 + k4);;
        x0 = x0 + h;
        printf("\n%.3f\t%.3f",x0,y);
    }
    break;
    case 3:
        exit(0);
}
}
return 0;
}