Maximum numbers

#include <stdio.h>

int main(int argc, char** argv)
{
    signed char sc;
    unsigned char uc;
    short signed int ss;
    short unsigned int us;
    signed int si;
    unsigned int ui;
    long signed int sl;
    long unsigned int ul;
    long long signed int sll;
    long long unsigned int ull;

    for(sc = 1; (signed char)(sc << 1) > sc; sc <<= 1, sc |= 1);
    for(uc = 1; (unsigned char)(uc << 1) > uc; uc <<= 1, uc |= 1);
    for(ss = 1; (short signed int)(ss << 1) > ss; ss <<= 1, ss |= 1);
    for(us = 1; (short unsigned int)(us << 1) > us; us <<= 1, us |= 1);
    for(si = 1; (signed int)(si << 1) > si; si <<= 1, si |= 1);
    for(ui = 1; (unsigned int)(ui << 1) > ui; ui <<= 1, ui |= 1);
    for(sl = 1; (long signed int)(sl << 1) > sl; sl <<= 1, sl |= 1);
    for(ul = 1; (long unsigned int)(ul << 1) > ul; ul <<= 1, ul |= 1);
    for(sll = 1; (long long signed int)(sll << 1) > sll; sll <<= 1, sll |= 1);
    for(ull = 1; (long long unsigned int)(ull << 1) > ull; ull <<= 1, ull |= 1);

    printf("Maximum signed char:\t%hd\n", sc);
    printf("Maximum unsigned char:\t%hu\n", uc);
    printf("Maximum short signed int:\t%hd\n", ss);
    printf("Maximum short unsigned int:\t%hu\n", us);
    printf("Maximum signed int:\t%d\n", si);
    printf("Maximum unsigned int:\t%u\n", ui);
    printf("Maximum long signed int:\t%ld\n", sl);
    printf("Maximum long unsigned int:\t%lu\n", ul);
    printf("Maximum long long signed int:\t%lld\n", sll);
    printf("Maximum long long unsigned int:\t%llu\n", ull);

    return 0;
}

gcc运行结果：

Maximum signed char:    127 
Maximum unsigned char:    255 
Maximum short signed int:    32767 
Maximum short unsigned int:    65535 
Maximum signed int:    2147483647 
Maximum unsigned int:    4294967295 
Maximum long signed int:    2147483647 
Maximum long unsigned int:    4294967295 
Maximum long long signed int:    9223372036854775807 
Maximum long long unsigned int:    18446744073709551615