Notes for printf and sprintf

■ Problem: After the user is required to input the file storage path, if the source contains a sprintf (buff, Incoming Force quota ), Once Incoming Force quota Contains "%", so the expected values in the buff may be different from the actual values. For example, if you enter the following path: C: \ Temp % sfile, then sprintf (path, "C: \ Temp % sfile"); Path Expected Value: C: \ Temp % sfile path actual value: C: \ Temp (null) file if you go to a path like fopen, obviously Program Problems may occur. Solution: Filter % before printf with the Escape Character "%" ■ problem: After requiring the user to input the path to save the file, if the source contains a sprintf (buff, Incoming Force quota ), Once Incoming Force quota Contains "%", so the expected values in the buff may be different from the actual values. For example, if you enter the following path: C: \ Temp % sfile, then sprintf (path, "C: \ Temp % sfile"); Path Expected Value: C: \ Temp % sfile path actual value: C: \ Temp (null) file if you go to a path like fopen, the program will obviously have a problem. Solution: Filter % before printf with the Escape Character "%" ■ question about % N void main () {int num1, num2; printf ("12345" % N 6789 % N \ N ", & num1, & num2) printf (" first count % d Second Count % d \ n ", num1, num2);} an asserted error is thrown after compiling and running vs2008: expression: ("'n' 'format specifier disabled", 0) ■ % A, % B, % C ...... % Z will not see this error, but % N is the original, In the printf family function, % N is used to obtain the number of printed strings. Printf ("12345" % N 6789 % N \ N ", & num1, & num2) when the above Code The result is num1 = 5, num2 = 9. However, due to security issues in the use of the printf function % N, it was often used by hackers, therefore, vs2008 is disabled by default. If % N is required, you can add the following code before using it: _ set_printf_count_output (INT enable); If the enable value is not 0, % N in the printf family function will be lifted.