too many characters in constant error

I get three errors with the below code snippet.  Can someone help me
with the syntax?

char *month = strtok_s(longDate, " ", &nextToken);
switch ( *month )
{
case 'March':
     a = 1;
     break;
case 'April':
     a = 2;
     break;
case 'May':
     a = 3;
     break;
default:
    break;
}

error C2015: too many characters in constant
error C2015: too many characters in constant
error C2196: case value '0' already used