读取文件信息，并通过sscanf从中获取所需数据

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

int file_length(char* fileName)
{
    FILE* fp;
    int file_set_val,file_end_val;    
    fp = fopen(fileName, "r");
    if(fp == NULL)
    {
        printf("[%s][%s]read file fail
",__LINE__,__FUNCTION__);
        return 0;
    }
    fseek(fp, 0 , SEEK_SET);
    file_set_val = ftell(fp);
    fseek(fp, 0 , SEEK_END);
    file_end_val = ftell(fp);    
    fclose(fp);
    return file_end_val-file_set_val;
}

int only_read_file(char* file_name_cp, char* read_content_cp, int read_len_i)
{
    FILE* fp;
    fp = fopen(file_name_cp, "r");
    if(fp == NULL)
    {
        printf("read file fail
");
        return -1;
    }
    fread(read_content_cp, read_len_i, 1, fp);
    fclose(fp);
    return 0;
}

int main(void)
{
    char* file_content = NULL;
    char buff[100] ={0};
    char* p = NULL;
    char* file_name = "123.txt";
    char* match_str = "weigth:";
    int length = 0;

    length = file_length(file_name);
    file_content = malloc(length);
    memset(file_content, 0, length);
    only_read_file(file_name, file_content, length);
    
    length = strlen(match_str);
    printf("length:%d
", length);
    p = strstr(file_content, match_str);
    if(p)
    {
        printf("p:%s
", p);
        sscanf(p+length, "%s", buff);    
    }
    printf("

buff:%s
", buff);
    return    0;
}