将 char 输入值与数组值进行比较

Question

I'm fairly new to coding. I am trying to compare char input value with array values, but it seems my code isn't comparing it (correctly) at all.

The code I have so far is:

int main() {
    int colunas = 5;
    int linhas = 6;
    char casa[80];
    char tabela[80][6][5] = {{"a5", "b5", "c5", "d5", "e5", "f5"},
                                      {"a4", "b4", "c4", "d4", "e4", "f4"},
                                      {"a3", "b3", "c3", "d3", "e3", "f3"},
                                      {"a2", "b2", "c2", "d2", "e2", "f2"},
                                      {"a1", "b1", "c1", "d1", "e1", "f1"}};
    scanf("%s", casa); 
      
    for (int i = 0;i< colunas; i++) {
        for (int j = 0;j < linhas; j++) {
            printf("%s",tabela[i][j]);

            // Problem happens here.
            if (casa == tabela[j][i]) {
                printf("Verdade");
            }
        }
        
        printf("\n"); 
    }
    printf("%s", casa);

    return 0;
}

Answer 1

Because C doesn't really have a string type, but instead a arrays of characters, the == will not work like it would with C++'s std::string or Rust's std::string::String.
Whats actually happening when you use == with arrays of characters, is that the arrays "decay" into pointers, and the == operator is actually just saying "is the memory location of casa the same memory location as tabela[j][i] "?
What you should do is use the standard library function strcmp (if you can, use strncmp as using strcmp can result in code vulnerabilities).
So instead of:

if (casa == tabela[j][i]) { /* CODE*/ }

do:

if (strcmp(casa, tabela[j][i]) == 0) { /* CODE*/ }

or even better:

if (strncmp(casa, tabela[j][i], 80) == 0) { /* CODE*/ }

You can find the man pages online for strncmp/strcmp and such online by just searching "foo man page" (where foo is obviously replaced with strncmp or something like that).