C语言结构体读写

实验环境fedora33 Qt5.12

背景 哈夫曼编码 每个结点包含了字符和对应的权值等信息，最好记录在文件里，每次运行代码从文件里读取结点信息

• 输入结点信息

#include <stdio.h>

typedef struct
{
    int weight;
    char myval;
}newnode;

void inputinfo(int n);

int main()
{
    int n;
    printf("give me a number
");
    scanf("%d",&n);
    inputinfo(n);
    return 0;
}


void inputinfo(int n)
{
    FILE* myfile;
    newnode mynode[3];
    newnode nnode;
    myfile = fopen("/home/saintding/文档/newplan.dat","a+");
    for(int i=0;i<n;i++)
    {
        printf("input char val
");
        scanf("%s",&nnode.myval);
        printf("input char weight
");
        scanf("%d",&nnode.weight);
        printf("Hello World!
");
        fwrite(&nnode,sizeof(newnode),1,myfile);
    }
    rewind(myfile);
    fclose(myfile);
}

• 读取结点信息

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
typedef struct
{
    int weight;
    char myval;
}newnode;

int main()
{
    FILE* fp;
    newnode nn;
    struct stat buf;//用于获取文件信息的结构体
    stat("/home/saintding/文档/newplan.dat",&buf);
    int rows = buf.st_size/sizeof(newnode);
    //struct stat buf = (struct stat*)malloc(sizeof(struct stat));
    fp = fopen("/home/saintding/文档/newplan.dat","rb");
    for(int i=0;i<rows;i++)
    {
        fread(&nn,sizeof(newnode),1,fp);
        printf("weight:%d,myval:%c
",nn.weight,nn.myval);

    }

    fclose(fp);
    printf("Hello World! %d
",rows);
    return 0;
}

输出效果图：

weight:7,myval:a
weight:32,myval:b
weight:18,myval:c
weight:5,myval:d
weight:25,myval:e
weight:13,myval:f
Hello World! 6
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