The ctype functions often need casts to be fully C standards compliant.
Here's the full explanation that I used to post to comp.lang.c from time
to time when the issue came up:
With the to*() and is*() functions, you should be careful to cast
`char' arguments to `unsigned char' before calling them. Type `char'
may be signed or unsigned, depending on your compiler or its
configuration. If `char' is signed, then some characters have
negative values; however, the arguments to is*() and to*() functions
must be nonnegative (or EOF). Casting to `unsigned char' fixes this
problem by forcing the character to the corresponding positive value.
This fixes the following warnings from some version of GCC:
lib/ofp-parse.c:828: warning: array subscript has type 'char'
lib/ofp-print.c:617: warning: array subscript has type 'char'
Reported-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Takayuki HAMA t-hama@cb.jp.nec.com
Teemu Koponen koponen@nicira.com
Vishal Swarankar vishal.swarnkar@gmail.com
+YAMAMOTO Takashi yamamoto@valinux.co.jp
Yongqiang Liu liuyq7809@gmail.com
kk yap yapkke@stanford.edu
} else {
parse_field_value(&fm->cr, f->index, value);
}
- } else if (!strncmp(name, "reg", 3) && isdigit(name[3])) {
+ } else if (!strncmp(name, "reg", 3)
+ && isdigit((unsigned char) name[3])) {
unsigned int reg_idx = atoi(name + 3);
if (reg_idx >= FLOW_N_REGS) {
ovs_fatal(0, "only %d registers supported", FLOW_N_REGS);
memcpy(name, port->name, sizeof name);
for (j = 0; j < sizeof name - 1; j++) {
- if (!isprint(name[j])) {
+ if (!isprint((unsigned char) name[j])) {
break;
}
}