運(yùn)算符	描述	示例
`+`	將兩個(gè)操作數(shù)相加	`A + B = 30`
`-`	從第一個(gè)操作數(shù)減去第二個(gè)操作數(shù)	`A ? B = -10`
`*`	將兩個(gè)操作數(shù)相乘	`A * B = 200`
`/`	將第一個(gè)操作數(shù)除以第二個(gè)操作數(shù)
`%`	模數(shù)運(yùn)算符和整數(shù)除法后的余數(shù)。	`B % A = 0`
`++`	遞增運(yùn)算符將整數(shù)值增加`1`。	`A++ = 11`
`--`	遞減運(yùn)算符將整數(shù)值減1。	`A-- = 9`

創(chuàng)建一個(gè)源代碼文件：arithmetic_operators.c，如下代碼 -

#include <stdio.h>

void main() {

   int a = 21;
   int b = 10;
   int c ;

   c = a + b;
   printf("Line 1 - Value of c is %d\n", c );

   c = a - b;
   printf("Line 2 - Value of c is %d\n", c );

   c = a * b;
   printf("Line 3 - Value of c is %d\n", c );

   c = a / b;
   printf("Line 4 - Value of c is %d\n", c );

   c = a % b;
   printf("Line 5 - Value of c is %d\n", c );

   c = a++; 
   printf("Line 6 - Value of c is %d\n", c );

   c = a--; 
   printf("Line 7 - Value of c is %d\n", c );
}

執(zhí)行上面示例代碼，得到以下結(jié)果 -

Line 1 - Value of c is 31
Line 2 - Value of c is 11
Line 3 - Value of c is 210
Line 4 - Value of c is 2
Line 5 - Value of c is 1
Line 6 - Value of c is 21
Line 7 - Value of c is 22
請(qǐng)按任意鍵繼續(xù). . .

2.關(guān)系運(yùn)算符

下表顯示了C語(yǔ)言支持的關(guān)系運(yùn)算符。假設(shè)變量A=10，變量B=20，則 -

運(yùn)算符	描述	示例
`==`	檢查兩個(gè)操作數(shù)的值是否相等。如果相等，則條件成立。	`(A == B)`結(jié)果為`false`
`!=`	檢查兩個(gè)操作數(shù)的值是否相等。如果值不相等，則條件成立。	`(A != B)` 結(jié)果為`true`
`>`	檢查左操作數(shù)的值是否大于右操作數(shù)的值。如果是，則條件成立。	`(A > B)` 結(jié)果為`false`
`<`	檢查左操作數(shù)的值是否小于右操作數(shù)的值。如果是，則條件成立。	`(A < B)`結(jié)果為`true`
`>=`	檢查左操作數(shù)的值是否大于等于右操作數(shù)的值。如果是，則條件成立。	`(A >= B)` 結(jié)果為`false`
`<=`	檢查左操作數(shù)的值是否小于等于右操作數(shù)的值。如果是，則條件成立。	`(A <= B)`結(jié)果為`true`

創(chuàng)建一個(gè)源代碼文件：relational_operators.c，如下代碼 -

#include <stdio.h>

main() {

   int a = 21;
   int b = 10;
   int c ;

   if( a == b ) {
      printf("Line 1 - a is equal to b\n" );
   }
   else {
      printf("Line 1 - a is not equal to b\n" );
   }

   if ( a < b ) {
      printf("Line 2 - a is less than b\n" );
   }
   else {
      printf("Line 2 - a is not less than b\n" );
   }

   if ( a > b ) {
      printf("Line 3 - a is greater than b\n" );
   }
   else {
      printf("Line 3 - a is not greater than b\n" );
   }

   /* Lets change value of a and b */
   a = 5;
   b = 20;

   if ( a <= b ) {
      printf("Line 4 - a is either less than or equal to  b\n" );
   }

   if ( b >= a ) {
      printf("Line 5 - b is either greater than  or equal to b\n" );
   }
}

執(zhí)行上面示例代碼，得到以下結(jié)果 -

Line 1 - a is not equal to b
Line 2 - a is not less than b
Line 3 - a is greater than b
Line 4 - a is either less than or equal to  b
Line 5 - b is either greater than  or equal to b
請(qǐng)按任意鍵繼續(xù). . .

3.邏輯運(yùn)算符

下表顯示了C語(yǔ)言支持的所有邏輯運(yùn)算符。假設(shè)變量A=1，變量B=0，則 -

運(yùn)算符	描述	示例
`&&`	邏輯與運(yùn)算符。如果兩個(gè)操作數(shù)都不為零，則條件成立。	`(A && B)`結(jié)果為`false`
	稱為邏輯或運(yùn)算符。如果兩個(gè)操作數(shù)中的任何一個(gè)非零，則條件成立。	(A B)結(jié)果為`true`
`!`	稱為邏輯非運(yùn)算符，它用于反轉(zhuǎn)其操作數(shù)的邏輯狀態(tài)。如果條件為真，則邏輯`NOT`運(yùn)算符將使其結(jié)果為`false`。

示例：創(chuàng)建一個(gè)源文件：logical_operators.c，代碼如下 -

#include <stdio.h>

main() {

   int a = 5;
   int b = 20;
   int c ;

   if ( a && b ) {
      printf("Line 1 - Condition is true\n" );
   }

   if ( a || b ) {
      printf("Line 2 - Condition is true\n" );
   }

   /* lets change the value of  a and b */
   a = 0;
   b = 10;

   if ( a && b ) {
      printf("Line 3 - Condition is true\n" );
   }
   else {
      printf("Line 3 - Condition is not true\n" );
   }

   if ( !(a && b) ) {
      printf("Line 4 - Condition is true\n" );
   }

}

執(zhí)行上面代碼，得到以下結(jié)果 -

Line 1 - Condition is true
Line 2 - Condition is true
Line 3 - Condition is not true
Line 4 - Condition is true

4.按位運(yùn)算符

按位運(yùn)算符對(duì)位進(jìn)行操作，并執(zhí)行逐位運(yùn)算。 ＆，|和^的真值表如下 -

p	q	p & q	p/q	p ^ q
0	0	0	0	0
0	1	0	1	1
1	1	1	1	0
1	0	0	1	1

假設(shè)A = 60，B = 13，二進(jìn)制格式如下：

A = 0011 1100

B = 0000 1101

-----------------

A&B = 0000 1100

A|B = 0011 1101

A^B = 0011 0001

~A = 1100 0011

下表列出了C語(yǔ)言支持的按位運(yùn)算符。假設(shè)變量A=60，變量B=13，則 -

運(yùn)算符	描述	示例
`&`	如果二進(jìn)制AND運(yùn)算符存在于兩個(gè)操作數(shù)中，則二進(jìn)制AND運(yùn)算符將對(duì)結(jié)果復(fù)制一位。	`(A&B)= 12`，即`0000 1100`
	二進(jìn)制OR運(yùn)算符如果存在于任一操作數(shù)中，則復(fù)制一位。	(A B) = 61, 即 `0011 1101`
`^`	二進(jìn)制XOR操作符復(fù)制該位，如果它設(shè)置在一個(gè)操作數(shù)中，而不是兩者。	`(A ^ B) = 49`, 即, `0011 0001`
`~`	二進(jìn)制補(bǔ)碼運(yùn)算符是一元的，具有“翻轉(zhuǎn)”位的作用。	`(~A)= -61`，即 `1100 0011`的補(bǔ)碼形式。
`<<`	二進(jìn)制左移操作符，左操作數(shù)值左移由右操作數(shù)指定的位數(shù)。	`A << 2 = 240` 即, `1111 0000`
`>>`	二進(jìn)制右移操作符，左操作數(shù)值被右操作數(shù)指定的位移動(dòng)。	`A >> 2 = 15` 即,`0000 1111`

示例： 創(chuàng)建一個(gè)源代碼文件：bitwise_operators.c，代碼如下所示 -

#include <stdio.h>

main() {

   unsigned int a = 60;    /* 60 = 0011 1100 */  
   unsigned int b = 13;    /* 13 = 0000 1101 */
   int c = 0;           

   c = a & b;       /* 12 = 0000 1100 */ 
   printf("Line 1 - Value of c is %d\n", c );

   c = a | b;       /* 61 = 0011 1101 */
   printf("Line 2 - Value of c is %d\n", c );

   c = a ^ b;       /* 49 = 0011 0001 */
   printf("Line 3 - Value of c is %d\n", c );

   c = ~a;          /*-61 = 1100 0011 */
   printf("Line 4 - Value of c is %d\n", c );

   c = a << 2;     /* 240 = 1111 0000 */
   printf("Line 5 - Value of c is %d\n", c );

   c = a >> 2;     /* 15 = 0000 1111 */
   printf("Line 6 - Value of c is %d\n", c );
}

執(zhí)行上面代碼，得到以下結(jié)果 -

Line 1 - Value of c is 12
Line 2 - Value of c is 61
Line 3 - Value of c is 49
Line 4 - Value of c is -61
Line 5 - Value of c is 240
Line 6 - Value of c is 15
請(qǐng)按任意鍵繼續(xù). . .

5.賦值運(yùn)算符

下表列出了C語(yǔ)言支持的賦值運(yùn)算符 -

運(yùn)算符	描述	示例
`=`	簡(jiǎn)單賦值運(yùn)算符，將右側(cè)操作數(shù)的值分配給左側(cè)操作數(shù)	`C = A + B`，將`A + B`的值分配給`C`
`+=`	相加與賦值運(yùn)算符。它將右操作數(shù)添加到左操作數(shù)，并將結(jié)果分配給左操作數(shù)。	`C + = A`等價(jià)于`C = C + A`
`-=`	相減與賦值運(yùn)算符。它從左操作數(shù)中減去右操作數(shù)，并將結(jié)果分配給左操作數(shù)。	`C -= A`等價(jià)于 `C = C - A`
`*=`	乘以與賦值運(yùn)算符。它將右操作數(shù)與左操作數(shù)相乘，并將結(jié)果分配給左操作數(shù)。	`C * = A`等價(jià)于`C = C * A`
`/=`	除以與賦值運(yùn)算符。它將左操作數(shù)與右操作數(shù)分開，并將結(jié)果分配給左操作數(shù)。	`C /= A`等價(jià)于`C = C / A`
`%=`	模數(shù)與賦值運(yùn)算符。它需要使用兩個(gè)操作數(shù)的模數(shù)，并將結(jié)果分配給左操作數(shù)。	`C %= A`等價(jià)于`C = C % A`
`<<=`	左移與賦值運(yùn)算符	`C <<= 2`等價(jià)于`C = C << 2`
`>>=`	右移與賦值運(yùn)算符	`C >> = 2`等價(jià)于`C = C >> 2`
`&=`	按位與賦值運(yùn)算符	`C &= 2`等價(jià)于`C = C & 2`
`^=`	按位異或運(yùn)算符和賦值運(yùn)算符。	`C ^= 2`等價(jià)于`C = C ^ 2`
	按位包含OR和賦值運(yùn)算符。

示例： 創(chuàng)建一個(gè)源文件：assignment_operators.c ，其代碼如下 -

#include <stdio.h>

void main() {

   int a = 21;
   int c ;

   c =  a;
   printf("Line 1 - =  Operator Example, Value of c = %d\n", c );

   c +=  a;
   printf("Line 2 - += Operator Example, Value of c = %d\n", c );

   c -=  a;
   printf("Line 3 - -= Operator Example, Value of c = %d\n", c );

   c *=  a;
   printf("Line 4 - *= Operator Example, Value of c = %d\n", c );

   c /=  a;
   printf("Line 5 - /= Operator Example, Value of c = %d\n", c );

   c  = 200;
   c %=  a;
   printf("Line 6 - %= Operator Example, Value of c = %d\n", c );

   c <<=  2;
   printf("Line 7 - <<= Operator Example, Value of c = %d\n", c );

   c >>=  2;
   printf("Line 8 - >>= Operator Example, Value of c = %d\n", c );

   c &=  2;
   printf("Line 9 - &= Operator Example, Value of c = %d\n", c );

   c ^=  2;
   printf("Line 10 - ^= Operator Example, Value of c = %d\n", c );

   c |=  2;
   printf("Line 11 - |= Operator Example, Value of c = %d\n", c );

}

執(zhí)行上面代碼，得到以下結(jié)果 -

Line 1 - =  Operator Example, Value of c = 21
Line 2 - += Operator Example, Value of c = 42
Line 3 - -= Operator Example, Value of c = 21
Line 4 - *= Operator Example, Value of c = 441
Line 5 - /= Operator Example, Value of c = 21
Line 6 - = Operator Example, Value of c = 11
Line 7 - <<= Operator Example, Value of c = 44
Line 8 - >>= Operator Example, Value of c = 11
Line 9 - &= Operator Example, Value of c = 2
Line 10 - ^= Operator Example, Value of c = 0
Line 11 - |= Operator Example, Value of c = 2
請(qǐng)按任意鍵繼續(xù). . .

6.其他操作符：sizeof和三元運(yùn)算符

除了上面討論的運(yùn)算符，還有一些其他重要的運(yùn)算符，包括sizeof和? ：也被C語(yǔ)言所支持。

運(yùn)算符	描述	示例
`sizeof()`	返回變量的大小	`sizeof(a)`，其中`a`為整數(shù)，將返回`4`。
`&`	返回變量的地址	`&a;` 返回變量的實(shí)際地址。
`*`	指向變量的指針	`*a;`
`? :`	條件表達(dá)式	如果條件是真的？那么返回值`X`：否則返回`Y`

示例： 創(chuàng)建一個(gè)源文件：sizeof_operator.c ，其代碼如下 -

#include <stdio.h>

void main() {

    int a = 4;
    short b;
    double c;
    int* ptr;

    /* example of sizeof operator */
    printf("Line 1 - Size of variable a = %d\n", sizeof(a));
    printf("Line 2 - Size of variable b = %d\n", sizeof(b));
    printf("Line 3 - Size of variable c= %d\n", sizeof(c));

    /* example of & and * operators */
    ptr = &a;    /* 'ptr' now contains the address of 'a'*/
    printf("value of a is  %d\n", a);
    printf("*ptr is %d.\n", *ptr);

    /* example of ternary operator */
    a = 10;
    b = (a == 1) ? 20 : 30;
    printf("Value of b is %d\n", b);

    b = (a == 10) ? 20 : 30;
    printf("Value of b is %d\n", b);
}

執(zhí)行上面代碼，得到以下結(jié)果 -

Line 1 - Size of variable a = 4
Line 2 - Size of variable b = 2
Line 3 - Size of variable c= 8
value of a is  4
*ptr is 4.
Value of b is 30
Value of b is 20
請(qǐng)按任意鍵繼續(xù). . .

7.運(yùn)算符優(yōu)先級(jí)

運(yùn)算符優(yōu)先級(jí)決定表達(dá)式中術(shù)語(yǔ)的分組，并決定如何評(píng)估計(jì)算表達(dá)式。某些運(yùn)算符的優(yōu)先級(jí)高于其他運(yùn)營(yíng)商; 例如，乘法運(yùn)算符的優(yōu)先級(jí)高于加法運(yùn)算符，則先要執(zhí)行乘法運(yùn)算符的運(yùn)算。

讓我們通過(guò)下面的例子了解優(yōu)先級(jí)：

int value = 10 + 20 * 10;

value變量計(jì)算結(jié)果為：210，因?yàn)?code>*(乘法運(yùn)算符)的優(yōu)先級(jí)比+(加法運(yùn)算符)高，所以在+(加法運(yùn)算符)之前進(jìn)行求值。

C語(yǔ)言運(yùn)算符的優(yōu)先級(jí)和關(guān)聯(lián)性如下：

分類	運(yùn)算符	關(guān)聯(lián)性
后綴	`() [] -> . ++ - -`	左到右
一元	`+ - ! ~ ++ - - (type)* & sizeof`	右到左
乘法	`* / %`	左到右
加法	`+ -`	左到右
位移	`<< >>`	左到右
關(guān)系	`< <= > >=`	左到右
等于	`== !=`	左到右
按位與	`&`	左到右
位異或	`^`	左到右
按位或	`/`	左到右
邏輯與	`&&`	左到右
邏輯或	`//`	左到右
條件	`?:`	右到左
賦值	`= += -= *= /= %=>>= <<= &= ^= /=`	右到左
逗號(hào)	`,`	左到右

示例： 創(chuàng)建一個(gè)源文件：operators_precedence.c ，其代碼如下 -

#include <stdio.h>

void main() {

    int a = 20;
    int b = 10;
    int c = 15;
    int d = 5;
    int e;

    e = (a + b) * c / d;      // ( 30 * 15 ) / 5
    printf("Value of (a + b) * c / d is : %d\n", e);

    e = ((a + b) * c) / d;    // (30 * 15 ) / 5
    printf("Value of ((a + b) * c) / d is  : %d\n", e);

    e = (a + b) * (c / d);   // (30) * (15/5)
    printf("Value of (a + b) * (c / d) is  : %d\n", e);

    e = a + (b * c) / d;     //  20 + (150/5)
    printf("Value of a + (b * c) / d is  : %d\n", e);

    return 0;
}

執(zhí)行上面代碼，得到以下結(jié)果 -

Value of (a + b) * c / d is : 90
Value of ((a + b) * c) / d is  : 90
Value of (a + b) * (c / d) is  : 90
Value of a + (b * c) / d is  : 50
請(qǐng)按任意鍵繼續(xù). . .

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C語(yǔ)言運(yùn)算符

1.算術(shù)運(yùn)算符

2.關(guān)系運(yùn)算符

3.邏輯運(yùn)算符

4.按位運(yùn)算符

5.賦值運(yùn)算符

6.其他操作符：sizeof和三元運(yùn)算符

7.運(yùn)算符優(yōu)先級(jí)