Greetings to all

I'm pretty much new to programming in C, so please excuse my mistakes. Since I'm a physics student, I mostly do applications of mathematical formulas and such. I've written a short code which should compute any Legendre polynomial for any l>0, using the formula P_l= ((2l+1)/l)*x*P_1- ((l-1)/l)*P_0.

I've developed the code in Dev-C++, and I can compile and run it. But whenever I type in the numbers needed, the program just closes abruptly! I honestly don't know what's the problem here, and that's why I'm posting this. If anyone could give me a hint, I would be most grateful. Thanks in advance!

Code:
#include <stdio.h>

int main(void){
    
    int l, i;
    float x, P[l];
    
    P[0]==1;
    P[1]==x;
    
    printf("Type in l i x\n");
    scanf("%n %f", &l, &x);
    

    if(l=0)
           printf("P = 1\n");
    else if(l=1)
         printf("P = x\n");
    else if(l>1)
    {for(i=1; i<l; i++)
    {P[l]=((2*l+1)/l)*x*P[1]-((l-1)/l)*P[0];
    P[0]==P[1];
    P[1]==P[l];}
    
    printf("The polynomial is: %f", P[l]);}
    
    getchar();
    getchar();
    return 0;}