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The C Programming Language does not explicitly specify this style, though it is followed consistently throughout the book.
From the book:. The position of braces is less important, although people hold passionate beliefs. We have chosen one of several popular styles.
Pick a style that suits you, then use it consistently. In old versions of the C language, argument types needed to be declared on the subsequent line i.
In this style, the constructs that allow insertions of new code lines are on separate lines, and constructs that prohibit insertions are on one line.
This principle is amplified by bracing every if, else, while, etc. Suggested advantages of this style are that the starting brace needs no extra line alone; and the ending brace lines up with the statement it conceptually belongs to.
There are many mentions of The One True Brace Style out there, but there is some confusion as to its true form.
The kernel style uses tab stops with the tab stops set every 8 characters for indentation. Opening curly braces of a function go to the start of the line following the function header.
Any other opening curly braces go on the same line as the corresponding statement, separated by a space. Labels in a switch statement are aligned with the enclosing block there is only one level of indents.
A single-statement body of a compound statement such as if, while, and do-while need not be surrounded by curly braces.
If, however, one or more of the substatements in an if-else statement require braces, then both substatements should be wrapped inside curly braces.
Line length is limited to 80 characters. The Linux-kernel style specifies that "if only one branch of a conditional statement is a single statement Some advocate mandatory braces for control statements with only a single statement in its scope, i.
Stroustrup does not indent the labels public: and private:. Also, in this style, while the opening brace of a function starts on a new line, the opening brace of a class is on the same line as the class name.
Stroustrup allows writing short functions all on one line. Stroustrup style is a named indentation style available in the editor Emacs.
Although mostly intended for kernel code, it is also widely used in userland code. The SunOS kernel and userland uses a similar indentation style.
The correctness of the indentation of a list of source files can be verified by the cstyle program written by Bill Shannon.
In this style, the hard tabulator ts in vi is kept at eight columns, while a soft tabulator is often defined as a helper also sw in vi , and set at four.
The hard tabulators are used to indent code blocks, while a soft tabulator four spaces of additional indentation is used for all continuing lines that must be split over multiple lines.
Moreover, function calls do not use a space before the parenthesis, although C language native statements such as if , while , do , switch and return do in the case where return is used with parens.
Functions that declare no local variables in their top-level block should also leave an empty line after their opening block brace.
The Allman style is named after Eric Allman. This style puts the brace associated with a control statement on the next line, indented to the same level as the control statement.
Statements within the braces are indented to the next level. This style is similar to the standard indentation used by the Pascal languages and Transact-SQL , where the braces are equivalent to the keywords begin and end.
Consequences of this style are that the indented code is clearly set apart from the containing statement by lines that are almost all whitespace and the closing brace lines up in the same column as the opening brace.
Some people feel this makes it easy to find matching braces. The blocking style also delineates the block of code from the associated control statement.
Commenting out or removing a control statement or block of code, or code refactoring , are all less likely to introduce syntax errors via dangling or missing braces.
Also, it is consistent with brace placement for the outer-function block. The style purportedly helps improve readability on projectors. Also, the indentation size and column restriction help create a visual cue for identifying excessive nesting of code blocks.
These advantages combine to help provide newer developers and learners implicit guidance to manage code complexity. The Whitesmiths style, also sometimes termed Wishart style, was originally used in the documentation for the first commercial C compiler, the Whitesmiths Compiler.
Whitesmiths, along with Allman , have been the most common bracing styles with equal popularity according to the Jargon File. This style puts the brace associated with a control statement on the next line, indented.
Statements within the braces are indented to the same level as the braces. The advantages of this style are similar to those of the Allman style. Blocks are clearly set apart from control statements.
The alignment of the braces with the block emphasizes that the full block is conceptually, and programmatically, one compound statement.
Indenting the braces emphasizes that they are subordinate to the control statement. Silyl triflate is more reactive and also converts ketones to silyl enol ethers.
Reaction with acids or fluorides such as tetra-n-butylammonium fluoride removes the silyl group when protection is no longer needed.
Larger substituents increase resistance to hydrolysis , but also make introduction of the silyl group more difficult. It is possible to monosilylate a symmetrical diol, although this is known to be problematic occasionally.
For example, the following monosilylation was reported: . However, it turns out that this reaction is hard to repeat. If the reaction were controlled solely by thermodynamics then, statistically, if the dianion is of similar reactivity to the monoanion, then a corresponding statistical mixture of disilylated:monosilylated:unsilylated diol will result.
However, the reaction in THF is made selective by two factors, kinetic deprotonation of the first anion AND the insolubility of the monoanion.
At the initial addition of TBSCl, there is only a minor amount of monoanion in solution with the rest being in suspension. This small portion reacts and shifts the equilibrium of the monoanion to draw more into solution, thereby allowing for high yields of the mono-TBS compound to be obtained.
Superior results in some cases may be obtained with butyllithium : . Selective deprotection of silyl groups is possible in many instances.
For example, in the synthesis of taxol : . Silyl ethers are mainly differentiated on the basis of sterics or electronics.
In general, acidic deprotections deprotect less hindered silyl groups faster, with the steric bulk on silicon being more significant than the steric bulk on oxygen.
Even forcing silylation techniques excess silyl chloride, dry pyridine, elevated temperatures were not successful. The use of 2. Corey assumed, that the reaction proceeds via N -tert-butyldimethylsilylimidazole as a very reactive silylating agent:.
However, newer research by P. Patschinski and H. Zipse shows, that the reaction is indeed catalyzed by DMF J.
Another key discovery by E. Nucleophilic attack of the small fluoride anion leads to a pentavalent silicon centre which is permitted due to hybridisation with the vacant d-orbitals of silicon.
In addition, the formation of the strong Si-F bond is the driving force for a fast cleavage:. Reactions of alcohols with silyl chlorides in the presence of N -methylimidazole were significantly accelerated by addition of iodine.
A general and high yielding method for efficient silylation of primary, secondary, and tertiary alcohols was developed.
Bartoszewicz, M. Kalek, J. Nilsson, R. Hiresova, J. Stawinski, Synlett , , A commercially available proazaphosphatrane is an efficient and mild catalyst for the silylation of a wide variety of alcohols and phenols, including acid-sensitive, base-sensitive, and hindered substrates, using tert -butyldimethylsilyl chloride TBDMSCl.
Although representative primary alcohols, secondary alcohols, and phenols were silylated using the more sterically hindered reagent tert -butyldiphenylsilyl chloride TBDPSCl , tertiary alcohols were recovered unchanged.
D'Sa, D. McLeod, J. Verkade, J. Tris pentafluorophenyl borane, B C 6 F 5 3 , is an effective catalyst for a mild and efficient dehydrogenative silation of alcohols using a variety of silanes.
Generally, the reactions are clean and high yielding, with dihydrogen as the only byproduct. Blackwell, K. Foster, V. Beck, W.
Piers, J. Porto, M. Vasconcellos, E. Ventura, F. Coelho, Synthesis , , Hf OTf 4 exhibits exceptionally high potency in desilylations.
A chemoselective cleavage of different silyl ethers or removal of TBS in the presence of most hydroxyl protecting groups was also accomplished.