Q: Is there a way to switch on strings?
A: Not directly. Sometimes, it's appropriate to use a separate function to map strings to integer codes, and then switch on those:
#define CODE_APPLE 1
#define CODE_ORANGE 2
#define CODE_NONE 0
switch(classifyfunc(string)) {
case CODE_APPLE:
...
case CODE_ORANGE:
...
case CODE_NONE:
...
}
where classifyfunc looks something like
static struct lookuptab {
char *string;
int code;
} tab[] = {
{"apple", CODE_APPLE},
{"orange", CODE_ORANGE},
};
classifyfunc(char *string)
{
int i;
for(i = 0; i < sizeof(tab) / sizeof(tab[0]); i++)
if(strcmp(tab[i].string, string) == 0)
return tab[i].code;
return CODE_NONE;
}
Otherwise, of course, you can fall back on a conventional if/else chain:
if(strcmp(string, "apple") == 0) {
...
} else if(strcmp(string, "orange") == 0) {
...
}
(A macro like
Streq()
from question 17.3
can make these comparisons a bit more convenient.)
See also questions 10.12, 20.16, 20.18, and 20.29.
References:
K&R1 Sec. 3.4 p. 55
K&R2 Sec. 3.4 p. 58
ISO Sec. 6.6.4.2
H&S Sec. 8.7 p. 248
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