C 編程運算符 · Programiz 中文系列教程

# C 編程運算符 > 原文： [https://www.programiz.com/c-programming/c-operators](https://www.programiz.com/c-programming/c-operators) #### 在本教程中，您將借助示例學習 C 編程中的不同運算符。運算符是對值或變量進行運算的符號。例如：`+`是執行加法的運算符。 C 具有廣泛的運算符來執行各種操作。 * * * ## C 算術運算符算術運算符對數值（常數和變量）執行數學運算，例如加，減，乘，除等。 | 運算符 | 運算符的含義 | | --- | --- | | `+` | 加法或一元加 | | `-` | 減法或一元減 | | `*` | 乘法 | | `/` | 除法 | | `%` | 除法后的余數（模） | ### 示例 1：算術運算符 ```c // Working of arithmetic operators #include <stdio.h> int main() { int a = 9,b = 4, c; c = a+b; printf("a+b = %d \n",c); c = a-b; printf("a-b = %d \n",c); c = a*b; printf("a*b = %d \n",c); c = a/b; printf("a/b = %d \n",c); c = a%b; printf("Remainder when a divided by b = %d \n",c); return 0; } ``` **輸出** ```c a+b = 13 a-b = 5 a*b = 36 a/b = 2 Remainder when a divided by b=1 ``` 如您所期望的，運算符`+`，`-`和`*`分別計算加法，減法和乘法。在正常計算中，`9/4 = 2.25`。但是，程序中的輸出為`2`。這是因為變量`a`和`b`都是整數。因此，輸出也是整數。編譯器忽略小數點后的術語，并顯示答案`2`而不是`2.25`。模運算符`%`計算余數。當`a=9`除以`b=4`時，其余為`1`。`%`運算符只能與整數一起使用。假設`a = 5.0`，`b = 2.0`，`c = 5`和`d = 2`。然后在 C 程式設計中 ```c // Either one of the operands is a floating-point number a/b = 2.5 a/d = 2.5 c/b = 2.5 // Both operands are integers c/d = 2 ``` * * * ## C 增減運算符 C 編程具有兩個運算符遞增`++`和遞減`--`，以將操作數（常量或變量）的值更改為 1。遞增`++`將值增加 1，而遞減`--`將值減少 1。這兩個運算符是一元運算符，這意味著它們僅對單個操作數進行運算。 ### 示例 2：遞增和遞減運算符 ```c // Working of increment and decrement operators #include <stdio.h> int main() { int a = 10, b = 100; float c = 10.5, d = 100.5; printf("++a = %d \n", ++a); printf("--b = %d \n", --b); printf("++c = %f \n", ++c); printf("--d = %f \n", --d); return 0; } ``` **輸出** ```c ++a = 11 --b = 99 ++c = 11.500000 ++d = 99.500000 ``` 在此，將運算符`++`和`--`用作前綴。這兩個運算符還可以用作`a++`和`a--`之類的后綴。訪問此頁面以了解有關[遞增和遞減運算符用作后綴](/article/increment-decrement-operator-difference-prefix-postfix "Increment Operator as postfix")時如何工作的更多信息。 * * * ## C 賦值運算符賦值運算符用于為變量賦值。最常見的賦值運算符是`=` | 運算符 | 示例 | 等價于 | | --- | --- | --- | | `=` | `a = b` | `a = b` | | `+=` | `a += b` | `a = a + b` | | `-=` | `a -= b` | `a = a - b` | | `*=` | `a *= b` | `a = a * b` | | `/=` | `a /= b` | `a = a / b` | | `%=` | `a %= b` | `a = a % b` | ### 示例 3：賦值運算符 ```c // Working of assignment operators #include <stdio.h> int main() { int a = 5, c; c = a; // c is 5 printf("c = %d\n", c); c += a; // c is 10 printf("c = %d\n", c); c -= a; // c is 5 printf("c = %d\n", c); c *= a; // c is 25 printf("c = %d\n", c); c /= a; // c is 5 printf("c = %d\n", c); c %= a; // c = 0 printf("c = %d\n", c); return 0; } ``` **輸出** ```c c = 5 c = 10 c = 5 c = 25 c = 5 c = 0 ``` * * * ### C 關系運算符關系運算符檢查兩個操作數之間的關系。如果該關系為真，則返回 1；否則為 0。如果該關系為假，則返回值 0。關系運算符用于[決策](/c-programming/c-if-else-statement "C if else")和[循環](/c-programming/c-for-loop "C for loop")中。 | 運算符 | 運算符含義 | 示例 | | --- | --- | --- | | `==` | 等于 | `5 == 3`求值為 0 | | `>` | 大于 | `5 > 3`求值為 1 | | `<` | 小于 | `5 < 3`求值為 0 | | `!=` | 不等于 | `5 != 3`求值為 1 | | `>=` | 大于或等于 | `5 >= 3`求值為 1 | | `<=` | 小于或等于 | `5 <= 3`求值為 0 | ### 示例 4：關系運算符 ```c // Working of relational operators #include <stdio.h> int main() { int a = 5, b = 5, c = 10; printf("%d == %d is %d \n", a, b, a == b); printf("%d == %d is %d \n", a, c, a == c); printf("%d > %d is %d \n", a, b, a > b); printf("%d > %d is %d \n", a, c, a > c); printf("%d < %d is %d \n", a, b, a < b); printf("%d < %d is %d \n", a, c, a < c); printf("%d != %d is %d \n", a, b, a != b); printf("%d != %d is %d \n", a, c, a != c); printf("%d >= %d is %d \n", a, b, a >= b); printf("%d >= %d is %d \n", a, c, a >= c); printf("%d <= %d is %d \n", a, b, a <= b); printf("%d <= %d is %d \n", a, c, a <= c); return 0; } ``` **輸出** ```c 5 == 5 is 1 5 == 10 is 0 5 > 5 is 0 5 > 10 is 0 5 < 5 is 0 5 < 10 is 1 5 != 5 is 0 5 != 10 is 1 5 >= 5 is 1 5 >= 10 is 0 5 <= 5 is 1 5 <= 10 is 1 ``` * * * ### C 邏輯運算符包含邏輯運算符的表達式返回 0 或 1，具體取決于表達式結果為`true`還是`false`。邏輯運算符通常用于 C 編程的[決策中](/c-programming/c-if-else-statement "C if else")。 | 運算符 | 含義 | 示例 | | --- | --- | --- | | `&&` | 邏輯與。僅當所有操作數均為真時為真 | 如果`c = 5`且`d = 2`，則表達式`((c==5) && (d>5))`等于 0。 | | <code>||</code> | 邏輯或。僅當任一操作數為真時為真 | 如果`c = 5`且`d = 2`，則表達式`((c==5) || (d>5))`等于 1。 | | `!` | 邏輯非。僅當操作數為 0 時為真 | 如果`c = 5`，則表達式`!(c==5)`等于 0。 | ### 示例 5：邏輯運算符 ```c // Working of logical operators #include <stdio.h> int main() { int a = 5, b = 5, c = 10, result; result = (a == b) && (c > b); printf("(a == b) && (c > b) is %d \n", result); result = (a == b) && (c < b); printf("(a == b) && (c < b) is %d \n", result); result = (a == b) || (c < b); printf("(a == b) || (c < b) is %d \n", result); result = (a != b) || (c < b); printf("(a != b) || (c < b) is %d \n", result); result = !(a != b); printf("!(a == b) is %d \n", result); result = !(a == b); printf("!(a == b) is %d \n", result); return 0; } ``` **輸出** ```c (a == b) && (c > b) is 1 (a == b) && (c < b) is 0 (a == b) || (c < b) is 1 (a != b) || (c < b) is 0 !(a != b) is 1 !(a == b) is 0 ``` **邏輯操作符**的說明 * `(a == b) && (c > 5)`的值為 1，因為兩個操作數`(a == b)`和`(c > b)`均為 1（真）。 * `(a == b) && (c < b)`的值為 0，因為操作數`(c < b)`為 0（假）。 * `(a == b) || (c < b)`的值為 1，因為`(a = b)`為 1（真）。 * `(a != b) || (c < b)`的值為 0，因為操作數`(a != b)`和`(c < b)`均為 0（假）。 * `!(a != b)`的值為 1，因為操作數`(a != b)`為 0（假）。因此，`!(a != b)`為 1（真）。 * `!(a == b)`的值為 0，因為`(a == b)`為 1（真）。因此，`!(a == b)`為 0（假）。 * * * ### C 按位運算符在計算過程中，數學運算（如加，減，乘，除等）被轉換為比特級，從而加快了處理速度并節省了電能。在 C 編程中使用按位運算符執行位級操作。 | 運算符 | 運算符的含義 | | --- | --- | | `&` | 按位與 | | <code>|</code> | 按位或 | | `^` | 按位異或 | | `~` | 按位補碼 | | `<<` | 左移 | | `>>` | 右移 | 訪問 C 中的[按位運算符以了解更多信息](/c-programming/bitwise-operators "C bitwise operators")。 ## 其他運算符 * * * ### 逗號運算符逗號運算符用于將相關表達式鏈接在一起。例如： ```c int a, c = 5, d; ``` * * * ### 大小運算符 `sizeof`是一元運算符，它返回數據的大小（常量，變量，數組，結構等）。 ### 示例 6：`sizeof`運算符 ```c #include <stdio.h> int main() { int a; float b; double c; char d; printf("Size of int=%lu bytes\n",sizeof(a)); printf("Size of float=%lu bytes\n",sizeof(b)); printf("Size of double=%lu bytes\n",sizeof(c)); printf("Size of char=%lu byte\n",sizeof(d)); return 0; } ``` **輸出** ```c Size of int = 4 bytes Size of float = 4 bytes Size of double = 8 bytes Size of char = 1 byte ``` * * * 三元運算符`?:`，引用運算符`&`，取消引用運算符`*`和成員選擇運算符`->`等其他運算符將在以后的教程中進行討論。