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Here, sizeof buffer is equivalent to 10 * sizeof buffer [0], which evaluates to 10, because the size of the type char is defined as 1. C99 adds support for flexible array members to structures. This form of array declaration is allowed as the last element in structures only, and differs from normal arrays in that no length is specified to the ...
char * pc [10]; // array of 10 elements of 'pointer to char' char (* pa)[10]; // pointer to a 10-element array of char The element pc requires ten blocks of memory of the size of pointer to char (usually 40 or 80 bytes on common platforms), but element pa is only one pointer (size 4 or 8 bytes), and the data it refers to is an array of ten ...
Byte, octet, minimum size of char in C99( see limits.h CHAR_BIT) −128 to +127 0 to 255 2 bytes 16 bits x86 word, minimum size of short and int in C −32,768 to +32,767 0 to 65,535 4 bytes 32 bits x86 double word, minimum size of long in C, actual size of int for most modern C compilers, [8] pointer for IA-32-compatible processors
C struct data types may end with a flexible array member [1] with no specified size: struct vectord { short len ; // there must be at least one other data member double arr []; // the flexible array member must be last // The compiler may reserve extra padding space here, like it can between struct members };
It should be noted that, since sizeof is a compile-time operation, it is impossible to use sizeof to determine the size of an array if it cannot be evaluated at compile time. That's incorrect since C99 introduces variable-length arrays. In that case, the size of the array can only be evaluated at run-time, and sizeof() will be evaluated at runtime.
A char (one byte) will be 1-byte aligned. A short (two bytes) ... Here is an example to allocate memory (double array of size 10) aligned to cache of 64 bytes.
If an array has unknown size (i.e. the array was an incomplete type), the number of initializers determines the size of the array and its type becomes complete: int x [] = { 0 , 1 , 2 } ; Compound designators can be used to provide explicit initialization when unadorned initializer lists might be misunderstood.
In both languages, a string is a primitive array of characters. In Pascal a string literal of length n is compatible with the type packed array [1..n] of char. In C a string generally has the type char[n]. Pascal has no support for variable-length arrays, and so any set of routines to perform string operations is dependent on a particular ...