How to write if in c language to judge multiple conditions

In C language, if statement is usually used to execute a specific block of code based on a single condition. However, multiple conditions can be combined to make a determination using logical operators such as &&, ||, and !. Including using logical AND (&&) to judge multiple conditions, using logical OR (||) to judge at least one condition, using logical NOT (!) to judge the negation of a single condition, as well as nesting if statements and using parentheses to clarify priority.

In C language, if statement is usually used to execute a specific block of code based on a single condition. However, if you want to execute code based on multiple conditions, you can use logical operators such as &&, ||, and ! to combine the conditions.

The following are some examples showing how to use if statements to determine multiple conditions in C language:

1. Use logical AND ( &&) Judge multiple conditions

When you want to check whether all conditions are true, you can use the logical AND operator &&.

c

##

#include <stdio.h>  
  
int main() {  
    int a = 5;  
    int b = 10;  
  
    if (a > 0 && b > 0) {  
        printf("a 和 b 都大于 0\n");  
    } else {  
        printf("至少有一个数不大于 0\n");  
    }  
  
    return 0;  
}

When you want to check that at least one condition is true, you can use the logical OR operator ||.

c

#include <stdio.h>  
  
int main() {  
    int a = -5;  
    int b = 10;  
  
    if (a > 0 || b > 0) {  
        printf("至少有一个数大于 0\n");  
    } else {  
        printf("两个数都不大于 0\n");  
    }  
  
    return 0;  
}

3. Use logical NOT (!) to determine the negation of a single condition

If you want to check if a condition is not true, you can use the logical NOT operator!.

c

#include <stdio.h>  
  
int main() {  
    int a = 0;  
  
    if (!a) {  
        printf("a 不等于 0\n"); // 实际上这里会打印，因为 a 等于 0，所以 !a 为真  
    } else {  
        printf("a 等于 0\n");  
    }  
  
    return 0;  
}

4. Nested if statements

For more complex conditional judgments, you can also use nested if statements.

c

##

#include <stdio.h>  
  
int main() {  
    int a = 5;  
    int b = 10;  
  
    if (a > 0) {  
        if (b > 0) {  
            printf("a 和 b 都大于 0\n");  
        } else {  
            printf("a 大于 0，但 b 不大于 0\n");  
        }  
    } else {  
        printf("a 不大于 0\n");  
    }  
  
    return 0;  
}

#include <stdio.h>  
  
int main() {  
    int x = 1;  
    int y = 2;  
    int z = 3;  
  
    if ((x == 1 && y == 2) || z == 3) {  
        printf("条件为真\n"); // 这里会打印，因为 (x == 1 && y == 2) 为真，或者 z == 3 也为真  
    } else {  
        printf("条件为假\n");  
    }  
  
    return 0;  
}

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