static const char *skipnum(const char *s, const char *e, readui_base base) {
for (;s<e;s++) {
unsigned int c = (unsigned char)*s;
if (cdigit(c)) {
if ( c-'0' >= (base & 0xFF) &&
!(base & READUI_ALLOWHIGHERDIGITS) )
break;
} else if (c>='A' && c<='Z') {
if (!(base & READUI_ALLOWCAPLETTERS))
break;
if ( c-'A'+10 >= (base & 0xFF) &&
!(base & READUI_ALLOWHIGHERDIGITS))
break;
} else if (c>='a' && c<='z') {
if (!(base & READUI_ALLOWLCASELETTERS))
break;
if ( c-'a'+10 >= (base & 0xFF) &&
!(base & READUI_ALLOWHIGHERDIGITS))
break;
} else
break;
}
return s;
}
int main(void)
{
int a;
printf("Enter an integer: ");
scanf("%d",&a);
printf("Number of digit 2:%d",cdigit(a,2));
return 0;
}
int cdigit(int num,int dig)
{
if(num)
{
if(num%10==dig)
{
num/=10;
return 1+cdigit(num,dig);
}
else{
num/=10;
return cdigit(num,dig);
}
}
else
{
return 0;
}
}
/*
* Scans past all the characters in a number token, fills the struct, and
* returns one of TOK_INTEGER or TOK_FLOATING to indicate the type.
*
* First character must be [0-9 '.']
*/
static enum token_type scan_number(struct scan_number *sn,
const char *s, const char *e) {
enum token_type type;
sn->dots_found = 0;
sn->prefix = s;
sn->digits = s;
if (s+3<=e && s[0]=='0') {
if (s[1]=='X' || s[1]=='x') {
//hexadecimal
s += 2;
sn->digits = s;
for (;s<e;s++) {
if (*s == '.')
sn->dots_found++;
else if (!chex(*s))
break;
}
goto done_scanning_digits;
} else if (s[1]=='B' || s[1]=='b') {
//binary
s += 2;
if (*s!='0' && *s!='1')
s -= 2;
sn->digits = s;
}
}
//binary, decimal, or octal
for (;s<e;s++) {
if (*s == '.')
sn->dots_found++;
else if (!cdigit(*s))
break;
}
done_scanning_digits:
sn->exponent = s;
if (s<e && (
(sn->prefix==sn->digits && (*s=='E' || *s=='e')) ||
(sn->prefix < sn->digits && (*s=='P' || *s=='p'))
)) {
s++;
if (s<e && (*s=='+' || *s=='-'))
s++;
while (s<e && cdigit(*s)) s++;
}
sn->suffix = s;
while (s<e && (cdigit(*s) || cletter(*s) ||
*s=='.' || *s=='_' || *s=='$')) s++;
sn->end = s;
//Now we're done scanning, but now we want to know what type this is
type = TOK_INTEGER;
if (sn->dots_found)
type = TOK_FLOATING;
if (sn->exponent < sn->suffix)
type = TOK_FLOATING;
//if this is an octal, make the leading 0 a prefix
if (type==TOK_INTEGER && sn->prefix==sn->digits &&
sn->digits < s && sn->digits[0]=='0')
sn->digits++;
return type;
}
