文件输入输出

• 用> 或者< 重定向

FILE

• FILE *fopen(const char * restrict path, const char * restrict mode);
• int fclose(FILE *stream);
• fscanf(FILE*, ...);
• fprintf(FILE*, ...);

打开文件的标准代码

FILE *fp = fopen(“file”,”r);

if ( fp ) {
    fscanf(fp,...);
    fclose(fp);
} else {
    ...
}

#include<stdio.h>

int main(int argc, char const *argv[])
{
    FILE *fp = fopen("12.in","r");
    if(fp){
        int num;
        fscanf(fp, "%d", &num);
        printf("%d", num);
        fclose(fp);
    } else {
        printf("无法打开文件\n");
    }
    
    return 0;
}

fopen