String inversion C language

Question

I have to do a show and almost finished the same.

Here’s what you ask for:

Palindrome is a phrase or word that keeps the same meaning when read backwards, for example bone, he, grate, etc. Make a program that reads a word of no more than 20 characters and print out whether this word is a palindrome or not.

This function should return 1 if the word is a palindrome, or 0, otherwise.

Input: A string. Output: Palindrome or Nao is a palindrome.

The problem is that the code reverses the string, but something is missing to fix and effectively compare the strings str and test

Used libraries (stdio.h, stdlib.h and string.h)

char str[20],teste[20]; // teste = cópia da str p/ testar condição palíndromo
int a,i,j,tam = 0;
scanf("%s",str);

for (i = 0, j = strlen(str); str[i] !='\0'; i++,j--){
    teste[j-1] = str[i];
    tam++;
}
    teste[j-1] = '\0';

for(i = 0; i < tam; i++){
    printf("%c",teste[i]); // imprime normalmente a string invertida na tela
}
printf("\n");

printf("%s\n",teste); // saída da string teste, porém nessa saída é possível ver que há mais caracteres inclusos na string e assim, invalidam a comparação que deverá ser feita.

return 0;
}

This is the final part of the code to be put in place of the printf("%s\n",teste); second-to-last line.

if(strcmp (str, teste) == 0){
    printf("Palindromo");
}else{
    printf("Nao e um palindromo");
}

I anticipate my thanks to those who can help!