ElDuderino420

{
    "#if !defined … #define … #endif": {
        "prefix": "def",
        "body": "#if !defined ${1/([A-Za-z0-9_]+).*/$1/}\n\t#define ${1:SYMBOL} ${2:value}\n#endif$0"
    },

    "#include \"…\"": {
        "prefix": "include",
        "body": "include \"${1:}\"$0"
    },