In C++ switch statement, the expression of each case label must be an integer constant expression.
For example, the following program fails in compilation.
/* Using non-const in case label */#include<stdio.h> int main() { int i = 10; int c = 10; switch(c) { case i: // not a "const int" expression printf("Value of c = %d", c); break; /*Some more cases */ } return 0; } |
Putting const before i makes the above program work.
#include<stdio.h> int main() { const int i = 10; int c = 10; switch(c) { case i: // Works fine printf("Value of c = %d", c); break; /*Some more cases */ } return 0; } |
Note : The above fact is only for C++. In C, both programs produce error. In C, using a integer literal does not cause error.
Program to find the largest number between two numbers using switch case:
#include<stdio.h> int main() { int n1=10,n2=11; //n1 > n2 (10 > 11) is false so using logical operator '>', n1 > n2 produces 0 //(0 means false, 1 means true) So, case 0 is executed as 10 > 11 is false. //Here we have used type cast to convert boolean to int, to avoid warning. switch((int)(n1 > n2)) { case 0: printf("%d is the largest
", n2); break; default: printf("%d is the largest
", n1); } //n1 < n2 (10 < 11) is true so using logical operator '>', n1 < n2 produces 1 //(1 means true, 0 means false) So, default is executed as we don't have case 1 to be executed. switch((int)(n1 < n2)) { case 0: printf("%d is the largest
", n1); break; default: printf("%d is the largest
", n2); } return 0; } //This code is contributed by Santanu |
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