指针变量中的乱码问题？
下面是我的代码：
#include<stdio.h>#include<stdlib.h>#include<string.h>#define N 20/*struct studentchange//定义结构体，将student中的定长记录改成变长记录{string name;string num;string age;string sex;};*/typedef struct studentchange//定义结构体，将student中的定长记录改成变长记录{char* name;char* num;char* tel;char* age;char* sex;}stud;struct studentindex//分别记录各个属性的长度，建立索引{int namelen;int numlen;int tellen;int agelen;int sexlen;int toallen;//一条记录的总共长度}studindex[N];stud studchange2[N];//存储从文件中读出来的记录信息/*struct studentc//记录每个studentindenx对象的长度{struct }*///定义一个为一页大小的块char buffer[1024];int contentlen;//一条记录的长度int contentlentotal=0;//所有记录的总长度；//用于存储从文件中读出来的信息 void strcopy(char a[],char b[],int n,int m);int main(){ //int attrLength(char*); char content[100]; int i,j;//定义通讯录stud stud[]={"Li","1001","18810366100","18","f", "Fun","1002","18810366101","19","m", "Wang1","1003","18810366102","17","f", "hei","1004","18810366103","18","f", "Gao","1005","18810366104","19","m", "Yu","1006","18810366105","17","f", "Feng","1007","18810366103","18","f", "Dou","1008","18810366104","19","m", "Wang2","1009","18810366105","17","f" , "Er","1010","18810366103","18","f", "San","1011","18810366104","19","m", "Zhao","1012","18810366105","17","f", "Qian","1013","18810366103","18","f", "Sun","1014","18810366104","19","m", "Li2","1015","18810366105","17","f", "Zhou","1016","18810366103","18","f", "Zheng","1017","18810366104","19","m", "Zhu","1018","18810366105","17","f" , "Xiaobai","1019","18810366103","18","f", "Meng","1020","18810366105","17","f"};//fstream iofile("studchange.dat",ios::in|ios::out|ios::binary);FILE *pf;if((pf=fopen("studchange.dat","ab+"))==NULL)//判断文件是否打开成功,一条记录一条记录追加printf("无法打开文件！"); for(i=0;i<N;i++){//为所有字段建立索引studindex[i].namelen=strlen(stud[i].name);printf("看看第%d条记录的姓名长度是：%d\n",i,studindex[i].namelen);// 测试一下studindex[i].numlen=strlen(stud[i].num);printf("看看第%d条记录的学号长度是：%d\n",i,studindex[i].numlen);// 测试一下studindex[i].tellen=strlen(stud[i].tel);printf("看看第%d条记录的电话长度是：%d\n",i,studindex[i].tellen);// 测试一下printf("0\n");studindex[i].agelen=strlen(stud[i].age);printf("0\n");studindex[i].sexlen=strlen(stud[i].sex);printf("看看第%d条记录的性别长度是：%d\n",i,studindex[i].sexlen);// 测试一下studindex[i].toallen=studindex[i].namelen+studindex[i].numlen+studindex[i].tellen+studindex[i].agelen+studindex[i].sexlen;printf("1\n");strcpy(content,stud[i].name);//将记录的各个属性拼接到一起printf("2\n");strcat(content,stud[i].num);strcat(content,stud[i].tel);strcat(content,stud[i].age);strcat(content,stud[i].sex);printf("看看第%d条记录的总信息是：%s\n",i,content);contentlen=strlen(content);//一条记录的长度fwrite(content,contentlen,1,pf);//将所有的记录写入文件中contentlentotal+=contentlen;contentlen=0;studchange2[i].name = (char *)malloc(10); //为结构体的每个成员分配内存空间 studchange2[i].num = (char *)malloc(10); studchange2[i].tel = (char *)malloc(20); studchange2[i].age = (char *)malloc(10); studchange2[i].sex = (char *)malloc(10);}fclose(pf);printf("\n");void query();void display();void update();char op;while(1){ printf("* Menu selection *\n"); printf("* 1.query *\n"); printf("* 2.display *\n"); printf("* 3.update *\n"); printf("* 4.exit *\n"); printf("* ****************************************\n"); printf("* Please enter selection:*"); scanf("%c",&op); switch(op) { case '1':query(); break; case '2':display(); break; case '3':update(); break; case '4':return 0; } getchar();}return 0; }void display() //打印文件中通讯录信息,并把读出来得记录放到结果体对象studchange2中。{ int i; FILE *pf2;if((pf2=fopen("studchange.dat","r+b"))==NULL)//判断文件是否打开成功,一条记录一条记录追加printf("无法打开文件！");char name[10];char num[10];char tel[20];char age[10];char sex[10];//将的信息输出到一个字符串中即可。int bufferlen=0;fread(buffer,contentlentotal,1,pf2);//将文件中的记录信息读到缓冲区中。printf("所有内容的长度是：%d\n",contentlentotal);printf("所有的记录信息是：%s\n",buffer);printf("**************** 通讯录 ******************\n");printf("姓名 学号 电话 年龄 性别\n");for(i=0;i<N;i++) //按照索引从文件中读出相应的记录，并把该记录复制给相应的结构体变量存储，便于其他操作。{ /*用strcpy之前，先把相关的字段用memset全部置为0，比如memset(stud.name, 0, 你用malloc给stud.name分配的字节数);这样就OK了。 */memset(studchange2[i].name,'\0',strlen(name)); strcopy(name,buffer,bufferlen,studindex[i].namelen);//将记录的一个属性提取出来memcpy(studchange2[i].name, name, strlen(name));//将name中的内容拷贝到给studchange2[i].name bufferlen+=studindex[i].namelen; memset(studchange2[i].num,'\0',strlen(num));strcopy( num,buffer,bufferlen,studindex[i].numlen);//将记录的一个属性提取出来memcpy(studchange2[i].num, num, strlen(num));//将name中的内容拷贝到给studchange2[i].name //studchange2[i].num=num;//将该条记录的该属性保存起来。 bufferlen+=studindex[i].numlen; memset(studchange2[i].tel,'\0',strlen(tel));strcopy(tel,buffer,bufferlen,studindex[i].tellen);//将记录的一个属性提取出来memcpy(studchange2[i].tel,tel, strlen(tel));//将name中的内容拷贝到给studchange2[i].name //studchange2[i].tel=tel;//将该条记录的该属性保存起来。 bufferlen+=studindex[i].tellen; memset(studchange2[i].age,'\0',strlen(age));strcopy( age,buffer,bufferlen,studindex[i].agelen);//将记录的一个属性提取出来memcpy(studchange2[i].age,age, strlen(age));//将name中的内容拷贝到给studchange2[i].namebufferlen+=studindex[i].agelen; memset(studchange2[i].sex,'\0',strlen(sex));strcopy( sex,buffer,bufferlen,studindex[i].sexlen);//将记录的一个属性提取出来memcpy(studchange2[i].sex,sex, strlen(sex));//将name中的内容拷贝到给studchange2[i].namebufferlen+=studindex[i].sexlen;printf("%s %s %s %s %s\n",studchange2[i].name,studchange2[i].num,studchange2[i].tel,studchange2[i].age,studchange2[i].sex);printf("\n");}//for循环}//函数体//将字符数组第m个到第n个字符copy到另外一个字符数组中void strcopy(char a[],char b[],int n,int m){ memcpy(a,&b[n],m); a[m]='\0';}
#include<stdio.h>#include<stdlib.h>#include<string.h>#define N 20/*struct studentchange//定义结构体，将student中的定长记录改成变长记录{string name;string num;string age;string sex;};*/typedef struct studentchange//定义结构体，将student中的定长记录改成变长记录{ char* name; char* num; char* tel; char* age; char* sex;}stud;struct studentindex//分别记录各个属性的长度，建立索引{ int namelen; int numlen; int tellen; int agelen; int sexlen; int toallen;//一条记录的总共长度}studindex[N];stud studchange2[N];//存储从文件中读出来的记录信息//定义一个为一页大小的块char g_buffer[1024];int contentlen;//一条记录的长度int contentlentotal=0;//所有记录的总长度；//用于存储从文件中读出来的信息void strcopy(char a[],char b[],int n,int m);int main(){ //int attrLength(char*); char content[100]; int i; //定义通讯录 stud stud[]={"Li","1001","18810366100","18","f", "Fun","1002","18810366101","19","m", "Wang1","1003","18810366102","17","f", "hei","1004","18810366103","18","f", "Gao","1005","18810366104","19","m", "Yu","1006","18810366105","17","f", "Feng","1007","18810366103","18","f", "Dou","1008","18810366104","19","m", "Wang2","1009","18810366105","17","f" , "Er","1010","18810366103","18","f", "San","1011","18810366104","19","m", "Zhao","1012","18810366105","17","f", "Qian","1013","18810366103","18","f", "Sun","1014","18810366104","19","m", "Li2","1015","18810366105","17","f", "Zhou","1016","18810366103","18","f", "Zheng","1017","18810366104","19","m", "Zhu","1018","18810366105","17","f" , "Xiaobai","1019","18810366103","18","f", "Meng","1020","18810366105","17","f"}; //fstream iofile("studchange.dat",ios::in|ios::out|ios::binary); FILE *pf; if((pf=fopen("studchange.dat","ab+"))==NULL)//判断文件是否打开成功,一条记录一条记录追加 printf("无法打开文件！"); for(i=0;i<N;i++) { //为所有字段建立索引 studindex[i].namelen=strlen(stud[i].name); printf("看看第%d条记录的姓名长度是：%d\n",i,studindex[i].namelen);// 测试一下 studindex[i].numlen=strlen(stud[i].num); printf("看看第%d条记录的学号长度是：%d\n",i,studindex[i].numlen);// 测试一下 studindex[i].tellen=strlen(stud[i].tel); printf("看看第%d条记录的电话长度是：%d\n",i,studindex[i].tellen);// 测试一下 printf("0\n"); studindex[i].agelen=strlen(stud[i].age); printf("0\n"); studindex[i].sexlen=strlen(stud[i].sex); printf("看看第%d条记录的性别长度是：%d\n",i,studindex[i].sexlen);// 测试一下 studindex[i].toallen=studindex[i].namelen+studindex[i].numlen+studindex[i].tellen+studindex[i].agelen+studindex[i].sexlen; printf("1\n"); strcpy(content,stud[i].name);//将记录的各个属性拼接到一起 printf("2\n"); strcat(content,stud[i].num); strcat(content,stud[i].tel); strcat(content,stud[i].age); strcat(content,stud[i].sex); printf("看看第%d条记录的总信息是：%s\n",i,content); contentlen=strlen(content);//一条记录的长度 fwrite(content,contentlen,1,pf);//将所有的记录写入文件中 contentlentotal+=contentlen; contentlen=0; studchange2[i].name = (char *)malloc(10); //为结构体的每个成员分配内存空间 studchange2[i].num = (char *)malloc(10); studchange2[i].tel = (char *)malloc(20); studchange2[i].age = (char *)malloc(10); studchange2[i].sex = (char *)malloc(10); ///////////////////////////////////////////////这里要初始化为0 memset(studchange2[i].name, 0, 10); memset(studchange2[i].num, 0, 10); memset(studchange2[i].tel, 0, 20); memset(studchange2[i].age, 0, 10); memset(studchange2[i].sex, 0, 10); } fclose(pf); printf("\n"); //void query(); void display(); //void update(); char op; while(1) { printf("* Menu selection *\n"); printf("* 1.query *\n"); printf("* 2.display *\n"); printf("* 3.update *\n"); printf("* 4.exit *\n"); printf("* ****************************************\n"); printf("* Please enter selection:*"); scanf("%c",&op); switch(op) { case '1': printf("query\n"); //query(); break; case '2': display(); break; case '3': //update(); printf("update\n"); break; case '4':return 0; } getchar(); } return 0; } void display() //打印文件中通讯录信息,并把读出来得记录放到结果体对象studchange2中。{ int i; FILE *pf2; if((pf2=fopen("studchange.dat","r+b"))==NULL)//判断文件是否打开成功,一条记录一条记录追加 printf("无法打开文件！"); //将的信息输出到一个字符串中即可。 int bufferlen=0; memset(g_buffer, 0, sizeof(g_buffer)); fread(g_buffer,contentlentotal,1,pf2);//将文件中的记录信息读到缓冲区中。 printf("所有内容的长度是：%d\n",contentlentotal); printf("所有的记录信息是：%s\n",g_buffer); printf("**************** 通讯录 ******************\n"); printf("姓名 学号 电话 年龄 性别\n"); char *buffer = g_buffer; for(i=0;i<N;i++) //按照索引从文件中读出相应的记录，并把该记录复制给相应的结构体变量存储，便于其他操作。 { strncpy(studchange2[i].name, buffer, studindex->namelen); buffer += studindex->namelen; strncpy(studchange2[i].num, buffer, studindex->numlen); buffer += studindex->numlen; strncpy(studchange2[i].tel, buffer, studindex->tellen); buffer += studindex->tellen; strncpy(studchange2[i].age, buffer, studindex->agelen); buffer += studindex->agelen; strncpy(studchange2[i].sex, buffer, studindex->sexlen); buffer += studindex->sexlen; printf("%s %s %s %s %s\n",studchange2[i].name,studchange2[i].num,studchange2[i].tel,studchange2[i].age,studchange2[i].sex); printf("\n"); }//for循环 }//函数体 //将字符数组第m个到第n个字符copy到另外一个字符数组中void strcopy(char a[],char b[],int n,int m){ memcpy(a,&b[n],m); a[m]='\0';}
[解决办法]
拷贝字符串的时候并没有把'\0'拷贝进去， 而且你初始化的时候也没有初始化为0， 所以造成乱码。
1.将分配后的内存初始化为0.
或者
2.拷贝完字符串后自己在字符串末尾添加一个'\0'
[解决办法]