为什么strtok_s在首次使用后返回0x00000001？

Question

I am facing some issues while using strtok_s . In the below code, read_data contains the string:

BEGIN_TRANSACTION CHANGE_0 PUT(debit_account,dbvalue.new)PUT(debit_account,dbvalue.new) CHANGE_0 PUT(credit_account,crvalue.new)PUT(credit_account,crvalue.new) OUTCOME_COMMITTED_0 END_TRANSACTION_0

Below is my code:

char *delim = " ";
char* next_token;
line[0] = strtok_s(read_data, delim, &next_token);
while (line[i] = strtok_s(NULL, delim, &next_token) != NULL)
{
    i++;
}

After execution, only line[0] contains correct string "BEGIN_TRANSACTION". All the other line[i] 's contains "0x00000001 ". I have looked up online but I am unable to find a solution here. Any help is appreciated.

Note: I am using Visual Studio 2010

Answer 1

while (line[i] = strtok_s(NULL, delim, &next_token) != NULL)

The above line should be as shown below. Note the brackets.

while ((line[i] = strtok_s(NULL, delim, &next_token)) != NULL)

To explain: The original while condition is not correct due to the operator order of precedence. It equates to:

line[i] = (strtok_s(NULL, delim, &next_token) != NULL)

Which means it takes the result of comparing the strtok_s return value to NULL and assigns that to line[i] . Which is why you get 1 for line[i] (except the last entry should be 0).