1.因为solc@0.5.1出现调用简单运算合约出现返回0的问题，所以把solc降到了0.4.22。
2.安装truffle后，npm install -g truffle,版本有所不同：
PS C:\> truffle version
Truffle v5.0.24 (core: 5.0.24)
Solidity v0.5.0 (solc-js)
Node v10.16.0
Web3.js v1.0.0-beta.37
3.建立简单合约Greeter.sol后，利用truffle compile后，出现：
Error: CompileError: ParsedContract.sol:1:1: ParserError: Source file requires different compiler version (current compiler is 0.5.8+commit.23d335f2.Emscripten.clang - note that nightly builds are considered to be strictly less than the released version
pragma solidity ^0.4.24;
^----------------------^
Compilation failed. See above.
4.修改truffle-config.js文件：
module.exports = {
// Uncommenting the defaults below
// provides for an easier quick-start with Ganache.
// You can also follow this format for other networks;
// see <http://truffleframework.com/docs/advanced/configuration>
// for more details on how to specify configuration options!
/*
networks: {
development: {
host: "127.0.0.1",
port: 7545,
network_id: "*"
},
test: {
host: "127.0.0.1",
port: 7545,
network_id: "*"
}
}
*/
compilers: {
solc: {
version: "0.4.24"
}
}
};
5.再次编译，出现
/C/users/administrator/webstormprojects/testtruffle/contracts/Migrations.sol:1:1: SyntaxError: Source file requires different compiler version (current compiler is 0.4.24+commit.e67f0147.Emscripten.clang - note that nightly builds are considered to be strictly less than the released version
pragma solidity >=0.4.25 <0.6.0;
^------------------------------^
6.打开Migrations.sol文件，
把pragma solidity >=0.4.25 <0.6.0;
修改为：pragma solidity >=0.4.24 <0.6.0;
编译通过。