compiler: unsigned number properly printed and converted to string

fix: array accessing now works with unsigned numbers

vlib/builtin/int.v

@@ -70,6 +70,34 @@ pub fn (nn int) str() string {
 	return tos(buf + max - len, len)
 }
 
+pub fn (nn u32) str() string {
+	 mut n := nn
+	if n == u32(0) {
+		return '0'
+	}
+	max := 16
+	mut buf := malloc(max)
+	mut len := 0
+	mut is_neg := false
+	if n < u32(0) {
+		n = -n
+		is_neg = true
+	}
+	// Fill the string from the end
+	for n > u32(0) {
+		d := n % u32(10)
+		buf[max - len - 1] = d + u32(`0`)
+		len++
+		n = n / u32(10)
+	}
+	// Prepend - if it's negative
+	if is_neg {
+		buf[max - len - 1] = `-`
+		len++
+	}
+	return tos(buf + max - len, len)
+}
+
 pub fn (nn u8) str() string {
 	 mut n := nn
 	if n == u8(0) {
@@ -126,6 +154,34 @@ pub fn (nn i64) str() string {
 	return tos(buf + max - len, len)
 }
 
+pub fn (nn u64) str() string {
+	 mut n := nn
+	if n == u64(0) {
+		return '0'
+	}
+	max := 32
+	mut buf := malloc(max)
+	mut len := 0
+	mut is_neg := false
+	if n < u64(0) {
+		n = -n
+		is_neg = true
+	}
+	// Fill the string from the end
+	for n > u64(0) {
+		d := n % u64(10)
+		buf[max - len - 1] = d + u64(`0`)
+		len++
+		n = n / u64(10)
+	}
+	// Prepend - if it's negative
+	if is_neg {
+		buf[max - len - 1] = `-`
+		len++
+	}
+	return tos(buf + max - len, len)
+}
+
 pub fn (b bool) str() string {
 	if b {
 		return 'true'

vlib/builtin/int_test.v

@@ -10,6 +10,26 @@ fn test_const() {
 	assert u == u64(1) 
 } 
 
+fn test_str_methods() {
+	assert i8(1).str() == '1'
+	assert i8(-1).str() == '-1'
+	assert i16(1).str() == '1'
+	assert i16(-1).str() == '-1'
+	assert i32(1).str() == '1'
+	assert i32(-1).str() == '-1'
+	assert i64(1).str() == '1'
+	assert i64(-1).str() == '-1'
+
+	assert u8(1).str() == '1'
+	assert u8(-1).str() == '255'
+	assert u16(1).str() == '1'
+	assert u16(-1).str() == '65535'
+	assert u32(1).str() == '1'
+	assert u32(-1).str() == '4294967295'
+	assert u64(1).str() == '1'
+	assert u64(-1).str() == '18446744073709551615'
+}
+
 /*
 fn test_cmp() {
 	assert 1 ≠ 2