Question

I’m having some issues with storing an address of a specific value in an array of strings to a pointer and printing it out. Please excuse the bad variable names, they are just for the example.

char **code;                      // code is an array of 100 strings of length 8 characters
code = malloc (100*sizeof(*code));
for (i=0; i<100; i++) {
    code[i]=malloc(8*sizeof(**code));
}

char **r;                        // r is an array of 16 strings of 32 characters
r = malloc (16*sizeof(*r));
for (i = 0; i < 16; i++)
    r[i] = malloc(32*sizeof(**r));

char *a;                         // a is a pointer to a string

a = (char *) &r[13];             // point a to value at r[13]

*a = (char *)&code[100];         // trying to assign the value of r[13] to the address of code[100]   

printf("Code 100 Add: %p a Val: %i\n", &code[100], *sp);  // trying to check values.

I’m trying to assign the value of a (which points to r[13], so assign value of r[13]) to the value of the Address of the string at code[100]. Is even a string of 32 characters the best way to do this?

Appreciate any help,
Gareth

Answer 1

a = (char *) &r[13];             // point a to value at r[13]

Turn on your compiler warnings, and pay attention to what the compiler tell you when you remove this cast. You shouldn’t need any casts in this code.

The type of r is char** and so the type of r[13] is char*, and the type of &r[13] is char**, which you’re assigning to a char*.

P.s., next time please also include the actual error you receive vs what you expected.