caffeine咖啡因
早安,這裡是咖啡因,我是一個準備升大一的快樂賣肝員,在這一個長達四個月的暑假,我沒有打算去打工,因此為了好好利用它,我打算認真學習多程式語言,甚至做成一篇篇教學,讓以後的我忘記時,還能回來快速回顧。所以,這裡就是我的學習紀錄,希望能我能持之以恆。
#include "stdio.h"
void text(){
printf("%d\n",a);
}
int main(void){
int a = 0;
text();}--------------------------------結果---------------------------------
’a’ was not declared in this scope
#include "stdio.h"int a = 1;int main(void){printf("%d\n",a);}--------------------------------結果---------------------------------1
#include "stdio.h"
int a = 1;
int main(void){int a = 2;
printf("%d\n",a);
}--------------------------------結果---------------------------------2
#include "stdio.h"
void text(){int a = 0;a++;
printf("%d\n",a);
}
int main(void){
text();
text();text();
}--------------------------------結果---------------------------------111
#include "stdio.h"
void text(){
static int a = 0;
a++;
printf("%d\n",a);
}
int main(void){
text();
text();
text();
}--------------------------------結果---------------------------------
1
2
3
(text.c)int b = 10;(main.c)#include "stdio.h"int main(void){extern int b;printf("%d",b);}--------------------------------結果---------------------------------10
#include "stdio.h"int main(void){auto int b = 0;printf("%d",b);}--------------------------------結果---------------------------------0
#include "stdio.h"
int main(void){
auto b = 0;
printf("%d",b);
}--------------------------------結果---------------------------------0
#include "stdio.h"#include "sys/time.h"int main(void){double sum = 0;double add = 1;struct timeval begin, end;gettimeofday(&begin, 0);register int a,i;//暫存器變數for (i=0; i<1000000000; i++){//主要執行內容a++;}gettimeofday(&end, 0);long seconds = end.tv_sec - begin.tv_sec;long microseconds = end.tv_usec - begin.tv_usec;double elapsed = seconds + microseconds*1e-6;printf("Time measured: %.3f seconds.\n", elapsed);return 0;}--------------------------------結果---------------------------------Time measured: 0.681 seconds.-------------------------------分隔線--------------------------------#include "stdio.h"
#include "sys/time.h"
int main(void){
double sum = 0;
double add = 1;
struct timeval begin, end;
gettimeofday(&begin, 0);
int a,i;//一般變數
for (i=0; i<1000000000; i++){//主要執行內容
a++;
}
gettimeofday(&end, 0);
long seconds = end.tv_sec - begin.tv_sec;
long microseconds = end.tv_usec - begin.tv_usec;
double elapsed = seconds + microseconds*1e-6;
printf("Time measured: %.3f seconds.\n", elapsed);
return 0;
}--------------------------------結果---------------------------------Time measured: 2.215 seconds.
#include "stdio.h"static int i;//靜態全域變數void text(){static int j;//靜態區域變數}
(text.c)static int i = 5;(main.c)#include "stdio.h"extern int i;int main(void){printf("%d",i);}--------------------------------結果---------------------------------