C语言：修订间差异

=== 保留关键字 ===▼

以下是ANSI/ISO C标准中定义的C语言的保留关键字：<ref>{{Cite web|url=https://www.iso.org/standard/57853.html|title=ISO/IEC 9899:2011|publisher=International Organization for Standardization|accessdate=2020-03-08|language=en|archiveurl=https://web.archive.org/web/20200328063511/https://www.iso.org/standard/57853.html|archivedate=2020-03-28|dead-url=no}}</ref>▼

{| class="wikitable" border="1" width="500" cellpadding="0" cellspacing="0"▼

|-----▼

| width="25%" | <tt>char</tt> || width="25%" | <tt>short</tt>▼

| width="25%" | <tt>int</tt> || width="25%" | <tt>unsigned</tt>▼

|-----▼

| width="25%" | <tt>long</tt> || width="25%" | <tt>float</tt>▼

| width="25%" | <tt>double</tt> || width="25%" | <tt>struct</tt>▼

|-----▼

| width="25%" | <tt>union</tt> || width="25%" | <tt>void</tt>▼

| width="25%" | <tt>enum</tt> || width="25%" | <tt>signed</tt>▼

|-----▼

| width="25%" | <tt>const</tt> || width="25%" | <tt>[[Volatile变量|volatile]]</tt>▼

| width="25%" | <tt>[[typedef]]</tt> || width="25%" | <tt>auto</tt>▼

|-----▼

| width="25%" | <tt>register</tt> || width="25%" | <tt>static</tt>▼

| width="25%" | <tt>extern</tt> || width="25%" | <tt>break</tt>▼

|-----▼

| width="25%" | <tt>case</tt> || width="25%" | <tt>continue</tt>▼

| width="25%" | <tt>default</tt> || width="25%" | <tt>do</tt>▼

|-----▼

| width="25%" | <tt>else</tt> || width="25%" | <tt>for</tt>▼

| width="25%" | <tt>goto</tt> || width="25%" | <tt>if</tt>▼

|-----▼

| width="25%" | <tt>return</tt> || width="25%" | <tt>switch</tt>▼

| width="25%" | <tt>while</tt> || width="25%" | <tt>sizeof</tt>▼

|}▼

<!-- sizeof不属于关键字，只属于运算符 -->▼

=== C99标准新增了以下关键字 ===：▼

{| class="wikitable" border="1" width="500" cellpadding="0" cellspacing="0"▼

|-----▼

| width="20%" | <tt>_Bool</tt> || width="20%" | <tt>_Complex </tt>▼

| width="20%" | <tt>_Imaginary</tt> || width="20%" | <tt>inline</tt>|| width="20%" | <tt>restrict</tt>▼

|}▼

=== C11标准新增了以下关键字 ===：▼

{| class="wikitable" border="1" width="500" cellpadding="0" cellspacing="0"▼

|-----▼

| width="20%" | <tt>_Alignas</tt> || width="20%" | <tt>_Alignof </tt>▼

| width="20%" | <tt>_Atomic</tt> || width="20%" | <tt>_Generic</tt>|| width="20%" | <tt>_Noreturn</tt>▼

|-----▼

| width="25%" | <tt>_Static_assert</tt>|| width="25%" | <tt>_Thread_local</tt>▼

|}▼

C语言的特色之一是：程序员必须亲自处理内存的分配细节。语言不负责内存边界检查，这是因为在运行时进行内存边界检查会造成[[性能问题]]，与[[Unix哲学|UNIX哲学]]不符。此特性容易导致[[缓冲区溢出]]问题。然而，部分编译器（如英特尔编译器）会出于安全性的考量，提供方法以进行运行时内存边界检查<ref>{{cite web |title=check-pointers, Qcheck-pointers |url=https://software.intel.com/content/www/us/en/develop/documentation/cpp-compiler-developer-guide-and-reference/top/compiler-reference/compiler-options/compiler-option-details/data-options/check-pointers-qcheck-pointers.html |website=Intel |accessdate=2021-06-01 |language=en}}</ref>。▼