c语言实现大小端判断和二进制模式写入各种数据到文件

#include <stdio.h>
#include <stdlib.h>
#include <inttypes.h>

//测试大小端模式
void test_endian()
{
uint32_t i=0x04030201;
unsigned char* cp=(unsigned char*)&i;
if(*cp==1)
printf("little-endian\n");
else if(*cp==4)
printf("big-endian\n");
else
printf("who knows?\n");
//exit(0);
}
void write_int()
{
int a=0x01001c00;//写入文件中变为00 1c 00 01,小端模式,从右往左
FILE* fp=fopen("int.bin","wb");
fwrite(&a,sizeof(a),1,fp);
fclose(fp);
printf("write_int ok!\n");
}
void write_int2()
{
int a=1024;//小端模式，转换为16进制写入
FILE* fp=fopen("int1024.bin","wb");
fwrite(&a,sizeof(a),1,fp);
fclose(fp);
printf("write_int2 ok!\n");
}
void write_float()
{
float a=1024.02;//小端模式,从右往左
FILE* fp=fopen("float.bin","wb");
fwrite(&a,sizeof(a),1,fp);
fclose(fp);
printf("write_float ok!\n");
}
void write_char()
{
char a='m';//小端模式,从右往左
FILE* fp=fopen("char.bin","wb");
fwrite(&a,sizeof(a),1,fp);
fclose(fp);
printf("write_char ok!\n");
}
void write_string2()
{
char *p;
FILE *fp;
char str[32]="example";
for(p=str;*p!=0;p++)
*p+=129;//将可见字符转换成不可见字符，不一定是加129
fp=fopen("string2.txt","w+") ;
fwrite(str,strlen(str),1,fp);
fclose(fp);

fp=fopen("string2.txt","r+") ;
fread(str,1,strlen(str),fp);
printf("%s\n",str);//在txt中显示的是乱码
for(p=str;*p!=0;p++) *p-=129;//转换成可见字符
printf("%s\n",str);
fclose(fp);
}

//fwrite(&a,strlen(a),1,fp);//以二进制形式对文件进行操作 不用使用fwrite了
//以文本形式写入
void write_string()
{
char* a="yunshouhu";//小端模式,从右往左
FILE* fp=fopen("string.txt","w");
fprintf(fp,"%s",a);
fclose(fp);
printf("write_string ok!\n");
}
//以文本形式读取
void read_string()
{
char line[1024]={0};
FILE* fp=fopen("string.txt","r");
int len=fscanf(fp,"%s",&line);
fclose(fp);
printf("read_string=%s len=%d\n",line,len);
}

//默认8的倍数对齐 4+1+10=15=>16
typedef struct Person
{
int age;
char sex;
char city[10];
} Person;

//默认8的倍数对齐 16+4+10=30=>32
typedef struct Student
{
Person parent;//16
int weight;
char classroom[10];
} Student;

//默认8的倍数对齐 4+4+10=18=>24
typedef struct Student2
{
Person* parent;//存在指针到文件中的话，指针对应的数据会丢失，因为你只存储了他的地址，没有保存他的数据
int weight;
char classroom[10];
} Student2;

void write_struct()
{
Person person;
person.age=26;
person.sex='m';
strcpy(person.city,"shenzhen");

FILE* fp=fopen("person.struct.bin","wb");
fwrite(&person,sizeof(person),1,fp);
fclose(fp);
printf("write_struct sizeof=%d ok!\n",sizeof(person));//16
}

void write_Student_struct()
{
Person person;
person.age=26;
person.sex='m';
strcpy(person.city,"shenzhen");

Student stu;
stu.parent=person;//16
stu.weight=140;
memset(stu.classroom,0,sizeof(stu.classroom));//清零，否则是随机值
strcpy(stu.classroom,"204");

FILE* fp=fopen("student.struct.bin","wb");
fwrite(&stu,sizeof(stu),1,fp);
fclose(fp);
printf("write_Student_struct sizeof=%d ok!\n",sizeof(stu));//32
}
void write_Student2_struct()
{
Person person;
person.age=26;
person.sex='m';
strcpy(person.city,"shenzhen");

Student2 stu;
stu.parent=&person;//16
stu.weight=140;
memset(stu.classroom,0,sizeof(stu.classroom));//清零，否则是随机值
strcpy(stu.classroom,"204");

FILE* fp=fopen("student2.struct.bin","wb");
fwrite(&stu,sizeof(stu),1,fp);
fclose(fp);
printf("write_Student2_struct sizeof=%d ok!\n",sizeof(stu));//24
}

//c语言实现大小端判断和二进制模式写入各种数据到文件。
int main(void)
{

test_endian();

write_int();
write_int2();
write_float();
write_char();
write_string();
read_string();

write_struct();
write_Student_struct();
write_Student2_struct();
printf("write ok!\n");

return 0;
}