Error: expected expression before ‘{’ token-CodePudding

I've tried to find this online, but all the other questions are about code that is nothing related to what I'm looking for. I'm trying to see if I can have multiple executing lines in a ternary operator:

#include <stdio.h>

int main()
{
    int i == 1;
    i = 1?{printf("H");printf("J")}:printf("H");
}

The output of this is the error:

Error: expected expression before ‘{’ token

What is wrong here to cause that?

CodePudding user response：

I'm trying to see if I can have multiple executing lines in a ternary operator

You can, using a comma operator

i = 1?printf("H"),printf("J"):printf("H");

CodePudding user response：

This error message is telling you that no, you can't have multiple executing lines in a ternary operator.

This is because the {} and all statements inside constitute a block, but not an expression. This is because, roughly speaking, the block, unlike an expression, does not have a value, and the ternary operator itself cannot output a value if one its branches doesn't have one. Consider: what value would a contain after the following?

auto a = 1 ? { printf("H"); printf("J") } : printf("H");

The ternary operator syntax has the form expression1 ? expression2: expression3.

CodePudding user response：

you can replace your line with:

printf(i==1? "HJ" : "H");