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doc: update the sqlite C interoperation example

pull/7402/head
Delyan Angelov 2020-12-18 22:31:49 +02:00
parent 8e6d2df131
commit b61a936fb8
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1 changed files with 7 additions and 4 deletions
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doc/docs.md
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@ -2720,7 +2720,7 @@ fn C.sqlite3_close(&C.sqlite3) int
fn C.sqlite3_column_int(stmt &C.sqlite3_stmt, n int) int
// ... you can also just define the type of parameter & leave out the C. prefix
// ... you can also just define the type of parameter and leave out the C. prefix
fn C.sqlite3_prepare_v2(&sqlite3, charptr, int, &&sqlite3_stmt, &charptr) int
fn C.sqlite3_step(&sqlite3_stmt)
@ -2732,9 +2732,11 @@ fn C.sqlite3_exec(db &sqlite3, sql charptr, FnSqlite3Callback voidptr, cb_arg vo
fn C.sqlite3_free(voidptr)
fn my_callback(arg voidptr, howmany int, cvalues &charptr, cnames &charptr) int {
unsafe {
for i in 0 .. howmany {
print('| ${cstring_to_vstring(cnames[i])}: ${cstring_to_vstring(cvalues[i]):20} ')
}
}
println('|')
return 0
}
@ -2744,9 +2746,10 @@ fn main() {
// passing a string literal to a C function call results in a C string, not a V string
C.sqlite3_open('users.db', &db)
// C.sqlite3_open(db_path.str, &db)
// you can also use `.str byteptr` field to convert a V string to a C char pointer
query := 'select count(*) from users'
stmt := &C.sqlite3_stmt(0)
// NB: you can also use the `.str` field of a V string,
// to get its C style zero terminated representation
C.sqlite3_prepare_v2(db, query.str, -1, &stmt, 0)
C.sqlite3_step(stmt)
nr_users := C.sqlite3_column_int(stmt, 0)