[C++知识库]C语言第一课2021.11.10

全局变量的寿命周期是整个程序；

局部变量的寿命周期是在当前的代码块；

#include<stdio.h>
int num1 = 100;//全局变量
int main()
{
?? ?
?? ?int age = 20;
?? ?int sum = 0;
?? ?int num1 = 100;
?? ?int num2 = 200;
?? ?char ch = 'A';
?? ?printf("%c\n", ch);//%C--打印字符格式的数据
?? ?printf("%d\n", age);
?? ?//short int-d短整型

?? ?printf("%d\n", sizeof(char));
?? ?printf("%d\n", sizeof(short));
?? ?printf("%d\n", sizeof(int));
?? ?printf("%d\n", sizeof(long));
?? ?printf("%d\n", sizeof(long long));
?? ?printf("%d\n", sizeof(float));
?? ?printf("%d\n", sizeof(double));
?? ?
?? ?scanf_s("%d%d", &num1, &num2);//输入num1num2
?? ?
?? ?sum = num1 + num2;
?? ?printf("sum=%d\n", sum);

?? ?return 0;
}