Validation of strings in C

Question

Good afternoon, I am learning C in college, and the following challenge has been proposed:

6. A seller needs an algorithm that calculates the total price due for a customer. The algorithm must receive the code of a product and the quantity purchased and calculate the total price using the table below. Display a message in case of invalid code.

      Código    Preço Unitário
   
      "ABCD"    R$ 5,30
   
      "XYPK"    R$ 6,00
   
      "KLMP"    R$ 3,20
   
      "QRST"    R$ 2,50
   

I realized that with switch would not be possible because the cases support only one character, so I built this structure with if:

#include <stdio.h>
#include <stdlib.h>
#include <locale.h>

int main()
{
setlocale(LC_ALL, "Portuguese");

char codigo;
int quantidade=0;
float preco= 0.00;

printf("Digite o código do produto: ");
scanf("%s", &codigo);



printf("Quantidade: ");
scanf("%i", &quantidade);

if(codigo == "ABCD"){
    preco = quantidade * 5.30;
    printf("O preço total é de R$%f", preco);
}else{
    if(codigo == "XYPK"){
        preco = quantidade * 6.00;
        printf("O preço total é de R$%f", preco);
    }
    else if(codigo == "KLMP"){
        preco == quantidade * 3.20;
        printf("O preço total é de R$%f", preco);
    }
    else if(codigo == "QRST"){
        preco == quantidade * 2,50;
        printf("O preço total é de R$%f", preco);

    }
}

Return 0; }

It turns out that the condition is not validated regardless of what I put in the scanf, can anyone help me with this situation? My program does not enter any IF!