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Memory vs Calldata

  1. memory: Typically used for function parameters and temporary variables within functions. Stored in memory and not persistent on the blockchain.

  2. calldata: Similar to memory, stored in memory and not persistent on the blockchain. The key difference is that calldata variables are immutable and commonly used for function parameters.

Learn more: Data location and assignment behavior

Below, we demonstrate how to write data using both calldata and memory

contract CalldataAndMemory {
struct Confi {
uint16 age;
string name;
string wish;
}

Confi John;
Confi Jane;

function writeToJohn(Confi calldata JohnData) external {
John = JohnData;
}

function writeToJane(Confi memory JaneData) external {
Jane = JaneData;
}
}

Recommendations for gas optimization:

🌟 In practical situations, if it's possible to use calldata, it is recommended to use calldata instead of memory.