Tips for C

1. If typeof is used as an expression, the expression is not executed. Only the type of the expression is obtained.

2. When ld is linked to a static database, you must first-o and then-l. This is because the ld does not automatically adjust the dependency sequence as it links to a dynamic library.

3, printf ("% f", 1/2); is the output 0.5? No, output 0. To output 0.5, write printf ("% f", (doublle) 1/(double)/2). This is because the C language uses the default value constant as the int type, int type operation. The result 0.5 is rounded to 0.

4. According to the C99 standard, 'A' is called an integer character constant and is regarded as an int type. Therefore, it occupies 4 bytes on 32-bit machines.
According to the iso c ++ standard, 'A' is called character literal, which is regarded as a char type and occupies 1 byte.

In this way, sizeof ('A') = 4 in the. c file, sizeof ('A') = 1 in the. cpp File

5. The number of initialization values can be less than the number of array elements. when the number of initialization values is less than the number of array elements, the corresponding values are initialized in order. The subsequent Initialization is 0 (Global or static array) or an uncertain value (partial array ).

Http://blog.csdn.net/sibylle/article/details/2026915

6. premature optimization is a sin