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What limits the number of nested loops in c?
你好。
当我读我的C书时，它说
Nesting for-Loop in C can continue even further up to 127 levels!
127是怎么来的？
我的书没有提到这个。对我来说就像一个神奇的数字。
[更新]
int main()
{
int number, n, triangularNumber, counter;
triangularNumber = 0;
for (counter = 1; counter <= 5; ++counter){
printf("What triangular number do you want? \n");
// using a routine called scanf
scanf("%i", &number);
triangularNumber = 0;
for (n =1 ; n <= number; ++n)
triangularNumber += n;
printf("Triangular number %i is %i\n", number, triangularNumber);
}
return 0;
}
这个数字来自 ISO C 标准，ISO/IEC 9899:1999 :
5.2.4.1 Translation limits
The implementation shall be able to
translate and execute at least one
program that contains at least one
instance of every one of the following
limits:
- 127 nesting levels of blocks
- 63 nesting levels of conditional inclusion
- 12 pointer, array, and function declarators (in any combinations)
modifying an arithmetic, structure,
union, or incomplete type in a
declaration
- 63 nesting levels of parenthesized declarators within a full declarator
- 63 nesting levels of parenthesized expressions within a full expression
- 63 significant initial characters in an internal identifier or a macro name
(each universal character name or
extended source character is
considered a single character)
- 31 significant initial characters in an external identifier (each universal
character name specifying a short
identifier of 0000FFFF or less is
considered 6 characters, each
universal character name specifying a
short identifier of 00010000 or more
is considered 10 characters, and each
extended source character is
considered the same number of
characters as the corresponding
universal character name, if any)
- 4095 external identifiers in one translation unit
- 511 identifiers with block scope declared in one block
- 4095 macro identifiers simultaneously defined in one
preprocessing translation unit
- 127 parameters in one function definition
- 127 arguments in one function call
- 127 parameters in one macro definition
- 127 arguments in one macro invocation
- 4095 characters in a logical source line
- 4095 characters in a character string literal or wide string literal
(after concatenation)
- 65535 bytes in an object (in a hosted environment only)
- 15 nesting levels for #included files
- 1023 case labels for a switch statement (excluding those for any
nested switch statements)
- 1023 members in a single structure or union
- 1023 enumeration constants in a single enumeration
- 63 levels of nested structure or union definitions in a single
struct-declaration-list
这些是符合标准的 C 编译器必须能够处理的最小值。