How can I compare strings in C using a `switch` statement?

Question

In C there is a switch construct which enables one to execute different conditional branches of code based on an test integer value, e.g.,

int a; /* Read the value of "a" from some source, e.g. user input */ switch (a) {   case 100:     // Code     break;   case 200:     // Code     break;   default:     // Code     break; } 

How is it possible to obtain the same behavior (i.e. avoid the so-called "if-else ladder") for a string value, i.e., a char *?

Answer 1

If you mean, how to write something similar to this:

// switch statement switch (string) {   case "B1":      // do something     break;   /* more case "xxx" parts */ } 

Then the canonical solution in C is to use an if-else ladder:

if (strcmp(string, "B1") == 0)  {   // do something }  else if (strcmp(string, "xxx") == 0) {   // do something else } /* more else if clauses */ else /* default: */ { } 

Answer 2

If you have many cases and do not want to write a ton of strcmp() calls, you could do something like:

switch(my_hash_function(the_string)) {     case HASH_B1: ...     /* ...etc... */ } 

You just have to make sure your hash function has no collisions inside the set of possible values for the string.