The C language provides a rich set of operators for performing various operations.1. Arithmetic Operators
| Operator | Description | Example |
| + | Addition | a + b |
| – | Subtraction | a – b |
| * | Multiplication | a * b |
| / | Division | a / b |
| % | Modulus (remainder) | a % b |
| ++ | Increment | a++ or ++a |
| — | Decrement | a– or –a |
#include <stdio.h>
int main(int argc, char *argv[]) { int a = 11; int b = 3; int c = 2; int e = 0; int f = 4; int g = 4;
printf("a + b = %d\n", (a + b)); printf("a - b = %d\n", (a - b)); printf("a * b = %d\n", (a * b)); printf("a / b = %d\n", (a / b)); printf("a %% b = %d\n", (a % b));
// c++ means use first, then c increments by 1 // here c's original value is 2, the meaning of use first is to set e=c, // then c increments by 1, so the first print outputs // c=3, e=2 // this complicated usage is generally avoided, usually only needed in exams/interviews e = c++;
printf("1. c=%d, e=%d\n", c, e);
// now c has become 3 // ++c means c increments by 1 first, then use // so here ++c, c becomes 4, then e=c, e also becomes 4. // this complicated usage is generally avoided, usually only needed in exams/interviews e = ++c;
printf("2. c=%d, e=%d\n", c, e);
// to avoid confusion between c++ and ++c, it can be used separately as below // through f++, ++g, the following printf outputs are all 5, without considering whether ++ is in front or behind // generally f++ is more common. f++; ++g; printf("1. f=%d, g=%d\n", f, g);
// -- and ++ have the same concept f--; --g; printf("2. f=%d, g=%d\n", f, g); return 0;}Output:
a + b = 14
a – b = 8
a * b = 33
a / b = 3
a % b = 2
1. c=3, e=2
2. c=4, e=4
1. f=5, g=5
2. f=4, g=4
2. Relational OperatorsGenerally used for comparisons
| Operator | Description | Example |
| == | Equal to | a == b |
| != | Not equal to | a != b |
| > | Greater than | a > b |
| < | Less than | a < b |
| >= | Greater than or equal to | a >= b |
| <= | Less than or equal to | a <= b |
#include <stdio.h>
int main(int argc, char *argv[]) { int a = 10; int b = 20;
if (a == b) { printf("a==b is true\n"); } else { printf("a==b is false\n"); }
if (a != b) { printf("a!=b is true\n"); } else { printf("a!=b is false\n"); }
if (a > b) { printf("a>b is true\n"); } else { printf("a>b is false\n"); }
if (a < b) { printf("a<b is true\n"); } else { printf("a<b is false\n"); }
if (a >= b) { printf("a>=b is true\n"); } else { printf("a>=b is false\n"); }
if (a <= b) { printf("a<=b is true\n"); } else { printf("a<=b is false\n"); } return 0;}Output:
a==b is false
a!=b is true
a>b is false
a<b is true
a>=b is false
a<=b is true
3. Logical Operators
| Operator | Description | Example |
| && | Logical AND | a && b |
| || | Logical OR | a || b |
| ! | Logical NOT | !a |
#include <stdio.h>
int main(int argc, char *argv[]) { int a = 5; int b = 6; // can also follow with && (b > 0), can have multiple conditions if ( (a > 0) && (b > a) ) { printf("If a is greater than 0 and b is greater than a, both conditions must be true, then it is true\n"); } // can also follow with || (b > 0), can have multiple conditions if ( (a > 2) || (a > b)) { printf("If a is greater than 2 or a is greater than b, as long as one condition is true, then it is true\n"); } if (!(a<0)) { printf("If a is less than 0 is false, then the opposite of false is true\n"); } return 0;}Output:
If a is greater than 0 and b is greater than a, both conditions must be true, then it is true
If a is greater than 2 or a is greater than b, as long as one condition is true, then it is true
If a is less than 0 is false, then the opposite of false is true
4. Bitwise OperatorsGenerally used less frequently
| Operator | Description | Example |
| & | Bitwise AND | a & b |
| | | Bitwise OR | a | b |
| ^ | Bitwise XOR | a ^ b |
| ~ | Bitwise NOT | ~b |
| << | Left Shift | a << 2 |
| >> | Right Shift | a >> 2 |
#include <stdio.h>
int main() { unsigned int a = 5; // Binary: 0101 unsigned int b = 3; // Binary: 0011
printf("a &b = %u\n", a & b); // 0101 & 0011 = 0001 (1) printf("a | b = %u\n", a | b); // 0101 | 0011 = 0111 (7) printf("a ^ b = %u\n", a ^ b); // 0101 ^ 0011 = 0110 (6) printf("~a = 0x%x\n", ~a); // 0x00000005 inverted 0xfffffffa printf("a << 1 = %u\n", a << 1); // 0101 << 1 = 1010 (10) printf("a >> 1 = %u\n", a >> 1); // 0101 >> 1 = 0010 (2)
return 0;}Output:
a & b = 1
a | b = 7
a ^ b = 6
~a = 0xfffffffa
a << 1 = 10
a >> 1 = 2
5. Assignment Operators
| Operator | Description | Example | Equivalent to |
| = | Simple assignment | a = b | |
| += | Add and assign | a += b | a = a + b |
| -= | Subtract and assign | a -= b | a = a – b |
| *= | Multiply and assign | a *= b | a = a * b |
| /= | Divide and assign | a /= b | a = a / b |
| %= | Modulus and assign | a %= b | a = a % b |
#include <stdio.h>
int main(int argc, char *argv[]) { int a = 10;
a += 5; // a = 15 printf("a+=5: %d\n", a); a -= 3; // a = 12 printf("a-=3: %d\n", a); a *= 2; // a = 24 printf("a*=2: %d\n", a); a /= 4; // a = 6 printf("a/=4: %d\n", a); a %= 4; // a = 2 printf("a%%=4: %d\n", a); return 0;}Output:
a+=5: 15
a-=3: 12
a*=2: 24
a/=4: 6
a%=4: 2