常用库函数&文件操作函数

#include <stdlib.h>

int (const void *a, const void *b)
{
    return *(int*)a - *(int*)b;
}

int main()
{
    int a;

    
    /*
    freopen("input.txt","r",stdin);
    */
    //读取和写入文本文件
    /*
    FILE* fp = fopen("input.txt","r");
    FILE* ofp = fopen("output.txt","w");
    while(fscanf(fp,"%d",&a) != EOF)
        fprintf(ofp,"%dn",a);
    fclose(fp);fclose(ofp);
    */
    //读取和写入二进制文件
    /*
    FILE* fp = fopen("input.txt","rb");
    FILE* ofp = fopen("output.txt","wb");
    char buf[6];
    int cnt;
    while(( cnt = fread(buf, sizeof(char), 6, fp)) != 0)
    {
        for(int i = 0; i < cnt; ++i) putchar(buf[i]);
        fwrite(buf, sizeof(char), cnt, ofp);
    }
    fclose(fp),fclose(ofp);
    */

    int as[10] = {0,2,5,8,7,4,1,3,6,9};
    qsort(as, 10, sizeof(int), cmp);
    for(int i = 0; i < 10; ++i) printf("%d ",as[i]);
    return 0;
}