C操作

 struct 結構
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#include<stdio.h>

//#include<stdlib.h>

int main(void){

struct score{

char sid[4];

int math;

}John={"s01",80},Tom={"s02",96};

printf("0: name chinese math\n");

printf("1: John %s %d\n",John.sid,John.math);

printf("2: Tom %s %d\n",Tom.sid,Tom.math);

return 0;

}

0: name chinese math

1: John s01     80

2: Tom  s02     96

結構指標

+++++++++++++++

//#include<stdlib.h>

#include<stdio.h>

void main(){

struct score{

char sid;

int math;

struct score *next;

};

typedef struct score stu;

stu John,Tom,*begin;

John.sid='J';

John.math=80;

John.next=NULL;

Tom.sid='T';

Tom.math=90;

Tom.next=NULL;

John.next=&Tom;

begin=&John;

printf("sid    math\n");

while(begin!=NULL){

printf("%c    %d    \n",begin->sid,begin->math);

begin=begin->next; 

}

}

sid    math

J    80

T    90

陣列模擬結構指標  saved as *.cpp

+++++++++++++++

//#include<stdlib.h>

//#include<stddef.h>

#include<stdio.h>

int main(void){

int stu[]={65,80,3,66,75,999};

int begin=0;

printf("sid    math\n");

while(begin!=999){

printf("%c    %d\n",stu[begin],stu[begin+1]);

begin=stu[begin+2]; 

}

return 0;

}

sid    math

A    80

B    75

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全域、區域變數

+++++++++++++++

#include<stdio.h>

//全域

int A=80;

void fun(){

        //區域2

int A=50;

printf("區域2前%d",A);

A=A+10;

printf("區域2後%d\n",A);

} 

int main(void){

printf("全域前=%d",A);

A=A+3;

printf("全域後%d\n",A);

//區域 

int A=0;

printf("區域前=%d",A);

for (int i=0;i<5;i++){

A=A+i;

printf("區域中%d",A);

printf(";");

}

A=A+3;

printf("區域後%d\n",A);

fun();

return 0;

}

全域前=80全域後83

區域前=0區域中0;區域中1;區域中3;區域中6;區域中10;區域後13

區域2前50區域2後60

交換2數 傳值 傳址

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#include<stdio.h>

void swap1(int x,int y){

int tmp;

tmp=x;

x=y;

y=tmp;

} 

void swap2(int *x,int *y){

int tmp;

tmp=*x;

*x=*y;

*y=tmp;

}

int main(void){

int x=10;

int y=0;

printf("初值 x=%d y=%d\n",x,y);

swap1(x,y);

printf("傳值 x=%d y=%d\n",x,y);

swap2(&x,&y);

printf("傳址 x=%d y=%d\n",x,y);

return 0;

}

初值 x=10 y=0

傳值 x=10 y=0

傳址 x=0 y=10

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