由于working是clientData，所以char *是一个简单字符。这与clientData[i]原型（期望使用指向以NULL结尾的字符串的char的指针）相冲突。

请注意，在分配它们之后，您永远不会初始化它们。这在运行时将是一个问题，因为createClient ()需要复制一些内容（至少要包含一个空字符串！）。

第二个错误要求您将malloc的结果强制转换为strdup ()（即使在很多情况下也可能会告诉您避免这样做，许多编译器都需要它）。

读取和创建操作可以合并。然后，在读取文件时，可以使用realloc增加客户端的数量。分配一个额外的结构以充当哨兵。或跟踪分配的结构数。
对于每种结构，请尝试从文件中读取四行，然后strdup行到结构指针。

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

typedef struct
{
    char *name;
    char *phoneNumber;
    char *location;
    char *traveltype;
} Client;

char *linefree ( char *line) {
    free ( line);
    return NULL;
}

Client *clientfree ( Client *client) {
    size_t count = 0;
    //the sentinel element will have name as NULL
    while ( client && client[count].name) {
        client[count].name = linefree ( client[count].name);
        client[count].phoneNumber = linefree ( client[count].phoneNumber);
        client[count].location = linefree ( client[count].location);
        client[count].traveltype = linefree ( client[count].traveltype);
        count++;
    }
    free ( client);
    return NULL;
}

void showclient ( Client *client) {
    size_t count = 0;
    //the sentinel element will have name as NULL
    while ( client && client[count].name) {
        printf ( "%s\n",client[count].name);
        if ( client[count].phoneNumber) {
            printf ( "   %s\n",client[count].phoneNumber);
        }
        if ( client[count].location) {
            printf ( "   %s\n",client[count].location);
        }
        if ( client[count].traveltype) {
            printf ( "   %s\n",client[count].traveltype);
        }
        count++;
    }
}

Client *readClientData ( char *filename) {
    size_t count = 0;
    FILE *pf = NULL;
    Client *client = NULL;
    Client *temp = NULL;
    if ( NULL == ( pf = fopen ( filename,"r"))) {
        perror ( filename);
        exit ( EXIT_FAILURE);
    }
    while ( 1) {
        // count + 2 to have sentinel element
        if ( NULL == ( temp = realloc ( client,sizeof *client * ( count + 2)))) {
            fprintf ( stderr,"realloc problem\n");
            return client;
        }
        client = temp;
        //set current element to NULL
        client[count].name = NULL;
        client[count].phoneNumber = NULL;
        client[count].location = NULL;
        client[count].traveltype = NULL;
        count++;
        //following serves as sentinel element
        client[count].name = NULL;
        client[count].phoneNumber = NULL;
        client[count].location = NULL;
        client[count].traveltype = NULL;

        char line[1024] = "";

        if ( ! fgets ( line,sizeof line,pf)) {
            fprintf ( stderr,"fgets EOF\n");
            break;
        }
        if ( NULL == ( client[count - 1].name = strdup ( line))) {
            fprintf ( stderr,"strdup name problem\n");
            break;
        }
        if ( ! fgets ( line,"fgets EOF\n");
            break;
        }
        if ( NULL == ( client[count - 1].phoneNumber = strdup ( line))) {
            fprintf ( stderr,"strdup phoneNumber problem\n");
            break;
        }
        if ( ! fgets ( line,"fgets EOF\n");
            break;
        }
        if ( NULL == ( client[count - 1].location = strdup ( line))) {
            fprintf ( stderr,"strdup location problem\n");
            break;
        }
        if ( ! fgets ( line,"fgets EOF\n");
            break;
        }
        if ( NULL == ( client[count - 1].traveltype = strdup ( line))) {
            fprintf ( stderr,"strdup traveltype problem\n");
            break;
        }
    }
    fclose ( pf);
    return client;
}

int main ( void) {
    char filename[1024] = "";
    printf ( "Enter a filename\n");
    if ( ! fgets ( filename,sizeof filename,stdin)) {
        fprintf ( stderr,"fgetline filename problem\n");
        exit ( EXIT_FAILURE);
    }
    filename[strcspn ( filename,"\n")] = 0;//remove trailing newline
    Client *client = readClientData ( filename);

    showclient ( client);

    client = clientfree ( client);

    return 0;
}