写了两天了，还是没写出来

[蟲蟲O_O]

学C已经两周了，感觉还是要动手写。写了两天手机号归属地查询，已经写了两天了各种问题，总是出不来结果，求各位帮帮新人
第一个是用的结构体的

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

typedef struct PHONE{
    char *phonenum;
    char *province;
    char *city;
    char *operators;
    char *code;
}PHONE;

PHONE *readFile( char *phonenum);

PHONE *readFile( char *phonenum){    
    //截取手机号前三位用来定位手机段
    char three[4] ;
    strncpy( three,phonenum,3 );
    
    //打开手机号段文件
    FILE * fp;
    fp = fopen(three, "r");
    if (fp == NULL){
        exit(EXIT_FAILURE);
    }
    char temp[8] ;
    strncpy( temp,phonenum,7);
    PHONE *phone =NULL ;
    int linecount = 0;
    while( !feof(fp) ){//文件未结束
        char line[256] ;
        fgets(line,256,fp);
        //截取第一个"|"为手机号段
        char *phonesection = strtok( line, "|");
        //截取第二个"|"为归属地
        char *area = strtok( NULL,"|");
        //截取第三个"|"为运营商
        char *operators = strtok(NULL,"|");
        //截取第四个"|"为城市编号
        char *code = strtok(NULL,"|");
        //省份
        char *province = strtok( area,",");
        //城市 
        char *city = strtok( NULL,",");

        if(strncmp( temp ,phonesection,7 ) == 0 ){
            phone = (PHONE *)malloc( sizeof (PHONE) );
            phone->phonenum = phonenum;
            phone->province = province;
            phone->city = city;
            phone->operators = operators;
            phone->code = code;          
            printf("%p,%p,%p,%p,%p\n", phone->phonenum,phone->province,phone->city,phone->operators,phone->code);
            printf("%s,%s,%s,%s,%s\n", phone->phonenum,phone->province,phone->city,phone->operators,phone->code);
            
            // printf("%p\n", phone);
            fclose( fp );
            return phone;
        }
        linecount++;
    }
   fclose( fp );

   return phone;
}

int main(int argc, char const *argv[]){
    char *phonenum = "13933007354";
 	PHONE *phone = readFile( phonenum);    
    printf("%p,%p,%p,%p,%p\n", phone->phonenum,phone->province,phone->city,phone->operators,phone->code);
    printf("%s,%s,%s,%s,%s\n", phone->phonenum,phone->province,phone->city,phone->operators,phone->code);
    // printf("%p\n", phone);
    free( phone );
    return 0;
}

内存地址相同，但是结果输出不正确

第二个是用数组的，完全就是走不通

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

char **readFile( char *phonenum);

char **readFile( char *phonenum){    
    //截取手机号前三位用来定位手机段
    char three[4];
    strncpy( three,phonenum,3 );
    
    //打开手机号段文件
    FILE * fp;
    fp = fopen(three, "r");
    if (fp == NULL){
        exit(EXIT_FAILURE);
    }
    char temp[8] ;
    strncpy( temp,phonenum,7);
    char *result[5];
    while( !feof(fp) ){//文件未结束
        char line[256] ;
        fgets(line,256,fp);
        //截取第一个"|"为手机号段
        char *phonesection = strtok( line, "|");
        //截取第二个"|"为归属地
        char *area = strtok( NULL,"|");
        //截取第三个"|"为运营商
        char *operators = strtok(NULL,"|");
        //截取第四个"|"为城市编号
        char *code = strtok(NULL,"|");
        //省份
        char *province = strtok( area,",");
        //城市 
        char *city = strtok( NULL,",");

        if(strncmp( temp ,phonesection,7 ) == 0 ){
            
            result[0] = phonenum;
            result[1] = province;
            result[2] = city;
            result[3] = operators;
            result[4] = code;          
            printf("%s,%s,%s,%s,%s\n", result[0],result[1],result[2],result[3],result[4]);
            fclose( fp );
            printf("%p\n", result);
            return result;
        }
    }
   fclose( fp );
   return result;
}

int main(int argc, char const *argv[]){
    char *phonenum = "13933007354";
 	char **result;
    result = readFile( phonenum );
    printf("%p\n", result);
    for( int i =0;i<5;i++){
        printf("%s\n", result[i]);
    }
    
    return 0;
}

求各位帮帮小弟

[w74839520]

学c两周水平就这么好了啊。

[忘世麒麟]

对于strncpy()函数，最常犯的一个错误是：认为无论如何目标位置上的字符串会以一个’\0′结尾，但实际情况不是这样的。strncpy(dst, src, n)的行为方式是： （1）至多从src拷贝n个char； （2）如果src中’\0’之前的字符数少于n，则’\0’将被作为填充字符写入dst直到写入dst的字符总数到达n； （3）如果src中的字符数大于等于n，那么仅前n个字符将被拷贝； （4）仅当src中的字符数少于n（不包括src中的’\0’）时dst中才会以’\0’结尾。 ------------------ typedef struct PHONE{ char *phonenum; char *province; char *city; char *operators; char *code; }PHONE; 要是嫌麻烦，可以将struct里面的指针都改写成数组。

[xionggch]

PHONE *phone =NULL ;

引用 1 楼 truelance 的回复:

typedef struct PHONE{ char *phonenum; char *province; char *city; char *operators; char *code; }PHONE; 这些指针都没分配空间，指向的是局部变量char line[256] 中的内容。 当函数返回时，这个空间就可能被改写掉了

typedef struct PHONE{ char phonenum[30]; char province[30]; char city[50]; char operators[30]; char code[30]; }PHONE; phone->phonenum = phonenum; //strcpy(phone->phonenum,phonenum); phone->province = province; phone->city = city; phone->operators = operators; phone->code = code;

[赵4老师]

strncpy(dst, src, n);dst[n]=0;

[赵4老师]

typedef struct {
    char phonenum [30];
    char province [30];
    char city     [50];
    char operators[30];
    char code     [30];
} PHONE;
PHONE ph,*phone;
phone=&ph;
strncpy(phone->phonenum  , phonenum ,30);phone->phonenum [30-1]=0;
strncpy(phone->province  , province ,30);phone->province [30-1]=0;
strncpy(phone->city      , city     ,50);phone->city     [50-1]=0;
strncpy(phone->operators , operators,30);phone->operators[30-1]=0;
strncpy(phone->code      , code     ,30);phone->code     [30-1]=0;

[蟲蟲O_O]

明白了 局部变量所指向的地址在函数结束后会释放掉内存，这时指向这些局部变量的指针会找不到对应的值 所以phone->phonenum是有值的，而其他却没有值 非常感谢各位

[赵4老师]

纠正楼上：

typedef struct {
    char phonenum [30];
    char province [30];
    char city     [50];
    char operators[30];
    char code     [30];
} PHONE;
PHONE ph,*phone;
phone=&ph;
strncpy(phone->phonenum  , phonenum ,30-1);phone->phonenum [30-1]=0;
strncpy(phone->province  , province ,30-1);phone->province [30-1]=0;
strncpy(phone->city      , city     ,50-1);phone->city     [50-1]=0;
strncpy(phone->operators , operators,30-1);phone->operators[30-1]=0;
strncpy(phone->code      , code     ,30-1);phone->code     [30-1]=0;

[熊熊大叔]

typedef struct PHONE{ char *phonenum; char *province; char *city; char *operators; char *code; }PHONE; 这些指针都没分配空间，指向的是局部变量char line[256] 中的内容。 当函数返回时，这个空间就可能被改写掉了