End of Life Ruby 3.1 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →
instance method
String#count
str.count([other_str]+) → integer
string.c
View on GitHub ↗
static VALUE
rb_str_count(int argc, VALUE *argv, VALUE str)
{
char table[TR_TABLE_SIZE];
rb_encoding *enc = 0;
VALUE del = 0, nodel = 0, tstr;
char *s, *send;
int i;
int ascompat;
size_t n = 0;
rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
tstr = argv[0];
StringValue(tstr);
enc = rb_enc_check(str, tstr);
if (argc == 1) {
const char *ptstr;
if (RSTRING_LEN(tstr) == 1 && rb_enc_asciicompat(enc) &&
(ptstr = RSTRING_PTR(tstr),
ONIGENC_IS_ALLOWED_REVERSE_MATCH(enc, (const unsigned char *)ptstr, (const unsigned char *)ptstr+1)) &&
!is_broken_string(str)) {
int clen;
unsigned char c = rb_enc_codepoint_len(ptstr, ptstr+1, &clen, enc);
s = RSTRING_PTR(str);
if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
send = RSTRING_END(str);
while (s < send) {
if (*(unsigned char*)s++ == c) n++;
}
return SIZET2NUM(n);
}
}
tr_setup_table(tstr, table, TRUE, &del, &nodel, enc);
for (i=1; i<argc; i++) {
tstr = argv[i];
StringValue(tstr);
enc = rb_enc_check(str, tstr);
tr_setup_table(tstr, table, FALSE, &del, &nodel, enc);
}
s = RSTRING_PTR(str);
if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
send = RSTRING_END(str);
ascompat = rb_enc_asciicompat(enc);
while (s < send) {
unsigned int c;
if (ascompat && (c = *(unsigned char*)s) < 0x80) {
if (table[c]) {
n++;
}
s++;
}
else {
int clen;
c = rb_enc_codepoint_len(s, send, &clen, enc);
if (tr_find(c, table, del, nodel)) {
n++;
}
s += clen;
}
}
return SIZET2NUM(n);
}
Each other_str parameter defines a set of characters to count. The intersection of these sets defines the characters to count in str. Any other_str that starts with a caret ^ is negated. The sequence c1-c2 means all characters between c1 and c2. The backslash character \ can be used to escape ^ or - and is otherwise ignored unless it appears at the end of a sequence or the end of a other_str.
Example
a = "hello world" a.count "lo" #=> 5 a.count "lo", "o" #=> 2 a.count "hello", "^l" #=> 4 a.count "ej-m" #=> 4 "hello^world".count "\\^aeiou" #=> 4 "hello-world".count "a\\-eo" #=> 4 c = "hello world\\r\\n" c.count "\\" #=> 2 c.count "\\A" #=> 0 c.count "X-\\w" #=> 3