C语言 类型提升

/* 编译选项：-ansi -pedantic
 */

#include 

int main(void) {
    char var0 = 0, var1 = 1;
    short var2 = 2, var3 = 3;

    printf("sizeof(char) == %d, sizeof(char + char) == %d\n",
           sizeof(var0), sizeof(var0 + var1));
    printf("sizeof(short) == %d, sizeof(short + short) == %d\n",
           sizeof(var2), sizeof(var2 + var3));

    return 0;
}
/* 运行结果 */
/*
sizeof(char) == 1, sizeof(char + char) == 4
sizeof(short) == 2, sizeof(short + short) == 4

Process returned 0 (0x0)   execution time : 0.016 s
Press any key to continue.
*/