Up to now, I have been learning C language for about half a year according to the school schedule, and I have only learned the Pointers in the basic learning. To be honest, my impression of C at first was that it was just a stepping stone to learn computer language, but I was very confused about how to apply C. It wasn’t until after the advanced language design course in the second half of my senior year that I tried dos’s complete little program running the graphical interface that I found the charm of C.
ok, no more nonsense, the following is my work of the second class — C language library management system. 1 simple little program. Is not purely original, is based on the network search “student management system” adapted from. I gained a lot by browsing and modifying a complete code directly. I think it’s more efficient, easy to understand, and easy to remember than boring code. Here are a few things I learned when I modified the program that were useful to me:
(this may be easy, but I really didn’t learn b before.)
1. Color setting of DOS interface (background, font color)
color [attr]
Here is the color code :(e.g. color fc produces bright red for bright white, 1st background, 2nd foreground)
0 = black 8 = gray 1 = blue 9 = light blue 2 = green A = light green 3 = lake blue B = light green 4 = red C = light red 5 = purple D = lavender 6 = yellow E = light yellow 7 = white F = bright white dos can only display these basic colors and can’t customize other colors
2. Comparison of strings (for password verification, etc.)
strcmp is a function prototype that compares strings: extern int strcmp(char *s1,char * s2); Usage: # include < string.h > Function: compare the strings s1 and s2. Note: when s1 < When s2, the value is returned < 0 when s1=s2, the return value =0 when s1 > When s2, the value is returned > 0
3. File operation in C language
Define a symbol (pointer variable) representing a file in the form FILE *fp
The statement that opens the file is
fopen(file location, open mode);
File location is the location where the file is located, e.g. D:// test.txt
There are several modes to turn on,
r (read) : read
w (write) : to write
a (append) : additional
t(text): text file that can be omitted without writing
b(banary): binary file
+ : read and write
1 is usually rt+, which can also be written as r+, and w+, which means read and write, and keep the original content. So open C and my :\my\ test.txt
fp = fopen (” c: / / my test txt ”, “r +”). Note that the folder symbol is different from above.
4. Code module (verify password, query information, modify information, delete information)
Security verification
void check()
{
char userName[5];/* The user name */
char userPWD[5];/* password */
int i,sum;
system("color 0B");
for(i = 1; i < 4; i++)
{
/* The username and password are both abcde;*/
printf(" ( The username and password are both abcde)\n\n");
printf("\n Please enter your user name :");
gets(userName);
printf("\n Please enter your password :");
gets(userPWD);
if ((strcmp(userName,"abcde")==0) && (strcmp(userPWD,"abcde")==0))/* Verify the username and password */
{
printf("\n * The user name and password are correct, and the main menu is displayed *");
return;
}
else
{
if (i < 3)
{
printf(" User name or password error, prompt user to enter again ");
printf(" The user name or password is wrong. Please enter it again !");
}
else
{
printf(" continuous 3 Enter the wrong user name or password the second time and exit the system. ");
printf(" You have been 3 If the user name or password is incorrectly entered this time, the system will exit !");
exit(1);
}
}
}
}Search for book information
void inquire(STUDENTS stu[])
{ int i;
char name[20];
system("cls");
printf(" \n\n Please enter the title of the book you are looking for: ");
scanf("%s",&name);
for(i=0;i<k;i++)
if(strcmp(name,stu[i].name)==0)
printf("\n\n\n No. : %d, Title: %s, The author: %s, Press: %s, The price : %.2f, Quantity: %d\n",stu[i].num,stu[i].name,
stu[i].author,stu[i].press,stu[i].price,stu[i].quantity);
printf(" Press any key to return to the main menu !");
scanf("%d",&i);
getchar();
}The principle is that through a loop, the student number stu[i] in all stu arrays is compared with the student number num to be queried.num is displayed if it is 1.
(3) modify the book information
The function is change(STUDENTS stu[]).
void change(STUDENTS stu[])
{ int num,i,choice;
system("cls");
printf("\n\n\n Please enter the number of the book you want to modify ");
scanf("%d",&num);
for(i=0;i<k;i++)
{ if(num==stu[i].num)
printf("\n No. : %d, Title: %s, The author: %s, Press: %s, The price : %.2f, Quantity: %d\n",stu[i].num,stu[i].name,
stu[i].author,stu[i].press,stu[i].price,stu[i].quantity);
printf("\n\n\n ******** Please enter the data you want to modify ********\n\n");
printf(" 1. Serial number \n\n");
printf(" 2. Title: \n\n");
printf(" 3. The author \n\n");
printf(" 4. Press. \n\n");
printf(" 5. The price \n\n");
printf(" 6. The number of \n\n");
printf(" Please select ( 1-6 ) :");
scanf("%d",&choice);
switch(choice)
{case 1:{
printf("\n Please enter the new number you changed ");
scanf("%d",&stu[i].num);
break;
}
case 2:{
printf("\n Please enter your new title ");
scanf("%s",stu[i].name);
break;
}
case 3:{
printf("\n Please enter your new author ");
scanf("%s",stu[i].author);
break;
}
case 4:{
printf("\n Please enter your new publisher ");
scanf("%s",stu[i].press);
break;
}
case 5:{
printf("\n Please enter your revised price ");
scanf("%f",&stu[i].price);
break;
case 6:{
printf("\n Please enter the new quantity you modified ");
scanf("%d",&stu[i].quantity);
break;
}
}
}The principle is to first locate and then enter a new value to replace the previous value.
Delete the book information
The function is void deletel(STUDENTS stu[])
The main principle is
printf(" Please enter the name of the book: ");
scanf("%s",Stuname2);
Let the user enter the name of the book and then compare each from scratch stu Names in variables
[csharp] view plain copy
if(strcmp(stu[i].name,Stuname2)==0)
for(j=0;j<20;j++)
stu[i].name[j]=stu[i+1].name[j];
k--;If a match is found, the next name overrides the first
Here is the complete main program code:
#include"stdio.h"
#include"stdlib.h"
#include"string.h"
#include"conio.h"
#define Pquantity 3
#define MAX 1000
#define N 5
int k=0;
/* Structural type */
typedef struct
{ int num;/* Serial number */
char name[20];/* Title: */
char author[20];/* The author */
char press[20];/* Press. */
float price;/* The price */
int quantity;/* The number of */
}STUDENTS;
int read_file(STUDENTS stu[])
{ FILE *fp;
int i=0;
if((fp=fopen("stu.txt","rt"))==NULL)
{printf("\n\n Stock file does not exist! Please create a ");
return 0;
}
while(feof(fp)!=1)
{
fread(&stu[i],sizeof(STUDENTS),1,fp);
if(stu[i].num==0)
break;
else
i++;
}
fclose(fp);
return i;
}
void save_file(STUDENTS stu[],int sum)
{FILE*fp;
int i;
if((fp=fopen("stu.txt","wb"))==NULL)
{printf(" File writing error !\n");
return;
}
for(i=0;i<sum;i++)
if(fwrite(&stu[i],sizeof(STUDENTS),1,fp)!=1)
printf(" File writing error !\n");
fclose(fp);
}
/* Creating book information */
int input(STUDENTS stu[])
{ int i,x;
for(i=0;i<1000;i++)
{
system("cls");
printf("\n\n Input book information ( most %d this )\n",MAX);
printf(" ----------------------------\n");
printf("\n The first %d This book ",k+1);
printf("\n Please enter the book number :");
scanf("%d",&stu[k].num);
printf("\n Please enter the title of the book :");
scanf("%s",stu[k].name);
printf("\n Please enter the author of the book :");
scanf("%s",stu[k].author);
printf("\n Please enter the publisher of the book :");
scanf("%s",stu[k].press);
printf("\n Please enter the price of the book :");
scanf("%f",&stu[k++].price);
printf("\n Please enter the number of books :");
scanf("%d",&stu[i].quantity);
printf("\n Please click 1 Key to return to menu or press 0 Key continues to create ");
scanf("%d",&x);
if(x)
break;
}
return k;
}
/* Delete book information */
void deletel(STUDENTS stu[])
{ system("cls");
char Stuname2[20];
int i,j;
printf(" Please enter the title of the book: ");
scanf("%s",Stuname2);
printf("\n");
for(i=0;i<k;i++)
if(strcmp(stu[i].name,Stuname2)==0)
for(j=0;j<20;j++)
stu[i].name[j]=stu[i+1].name[j];
k--;
printf(" Delete the success \n");
printf(" Press any key to return to the main menu !");
scanf("%d",&i);
getchar();
}
/* Print book information */
void output(STUDENTS stu[])
{ system("cls");
int i;
for(i=0;i<k;i++)
printf(" No. : %d, Title: %s, The author: %s, Press: %s, The price : %.2f, Quantity: %d\n",stu[i].num,stu[i].name,
stu[i].author,stu[i].press,stu[i].price,stu[i].quantity);
printf(" Press any key to return to the main menu !");
scanf("%d",&i);
getchar();
}
/* Search for book information */
void inquire(STUDENTS stu[])
{ int i;
char name[20];
system("cls");
printf(" \n\n Please enter the title of the book you are looking for: ");
scanf("%s",&name);
for(i=0;i<k;i++)
if(strcmp(name,stu[i].name)==0)
printf("\n\n\n No. : %d, Title: %s, The author: %s, Press: %s, The price : %.2f, Quantity: %d\n",stu[i].num,stu[i].name,
stu[i].author,stu[i].press,stu[i].price,stu[i].quantity);
printf(" Press any key to return to the main menu !");
scanf("%d",&i);
getchar();
}
/* Modify book information */
void change(STUDENTS stu[])
{ int num,i,choice;
system("cls");
printf("\n\n\n Please enter the number of the book you want to modify ");
scanf("%d",&num);
for(i=0;i<k;i++)
{ if(num==stu[i].num)
printf("\n No. : %d, Title: %s, The author: %s, Press: %s, The price : %.2f, Quantity: %d\n",stu[i].num,stu[i].name,
stu[i].author,stu[i].press,stu[i].price,stu[i].quantity);
printf("\n\n\n ******** Please enter the data you want to modify ********\n\n");
printf(" 1. Serial number \n\n");
printf(" 2. Title: \n\n");
printf(" 3. The author \n\n");
printf(" 4. Press. \n\n");
printf(" 5. The price \n\n");
printf(" 6. The number of \n\n");
printf(" Please select ( 1-6 ) :");
scanf("%d",&choice);
switch(choice)
{case 1:{
printf("\n Please enter the new number you changed ");
scanf("%d",&stu[i].num);
break;
}
case 2:{
printf("\n Please enter your new title ");
scanf("%s",stu[i].name);
break;
}
case 3:{
printf("\n Please enter your new author ");
scanf("%s",stu[i].author);
break;
}
case 4:{
printf("\n Please enter your new publisher ");
scanf("%s",stu[i].press);
break;
}
case 5:{
printf("\n Please enter your revised price ");
scanf("%f",&stu[i].price);
break;
case 6:{
printf("\n Please enter the new quantity you modified ");
scanf("%d",&stu[i].quantity);
break;
}
}
}
printf(" No. : %d, Title: %s, The author: %s, Press: %s, The price : %.2f, Quantity: %d\n",stu[i].num,stu[i].name,
stu[i].author,stu[i].press,stu[i].price,stu[i].quantity);
printf(" Press any key to return to the main menu !");
scanf("%d",&i);
break;
}
}
/* Book price information ranking */
void sort(STUDENTS stu[])
{ int i,j,n=1,x;
system("cls");
int t;
for(i=0;i<k-1;i++)
for(j=i+1;j<k;j++)
if(stu[i].price<stu[j].price)
{ t=stu[i].price;
stu[i].price=stu[j].price;
stu[j].price=t;
t=stu[i].num;
stu[i].num=stu[j].num;
stu[j].num=t;
}
for(i=0;i<k;i++)
printf(" ranking Serial number The price \n %d %d %.2f\n",n++,stu[i].num,stu[i].price);
printf(" Press any key to return to the main menu !");
scanf("%d",&x);
getchar();
}
void pquantitydis()
{
printf(" \n\n\n **********************************\n");
printf(" * *\n");
printf(" * *\n");
printf(" * *\n");
printf(" * Welcome to the book information management system *\n");
printf(" * *\n");
printf(" * *\n");
printf(" * *\n");
printf(" **********************************\n");
}
void check()
{
char userName[5];/* The user name */
char userPWD[5];/* password */
int i,sum;
system("color 0B");
for(i = 1; i < 4; i++)
{
/* The username and password are both abcde;*/
printf(" ( The username and password are both abcde)\n\n");
printf("\n Please enter your user name :");
gets(userName);
printf("\n Please enter your password :");
gets(userPWD);
if ((strcmp(userName,"abcde")==0) && (strcmp(userPWD,"abcde")==0))/* Verify the username and password */
{
printf("\n * The user name and password are correct, and the main menu is displayed *");
return;
}
else
{
if (i < 3)
{
printf(" User name or password error, prompt user to enter again ");
printf(" The user name or password is wrong. Please enter it again !");
}
else
{
printf(" continuous 3 Enter the wrong user name or password the second time and exit the system. ");
printf(" You have been 3 If the user name or password is incorrectly entered this time, the system will exit !");
exit(1);
}
}
}
}
void menu()
{
STUDENTS stu[20];
int choice,k,sum;
sum=read_file(stu);
if(sum==0)
{ printf(" First input basic inventory information! Press enter to enter -- \n");
getch();
sum=input(stu);
}
do
{ system("cls");
printf("\n\n\n ******** Book information management system ********\n\n");
printf(" 1. Creating book information \n\n");
printf(" 2. Print book information \n\n");
printf(" 3. Search for book information \n\n");
printf(" 4. Modify book information \n\n");
printf(" 5. Delete book information \n\n");
printf(" 6. Book price information ranking \n\n");
printf(" 0. Log out \n\n");
printf(" Please select ( 0-6 ) :");
scanf("%d",&choice);
switch(choice)
{
case 1: k=input(stu); break;/* Creating book information */
case 2: output( stu) ; break;/* Print book information */
case 3: inquire(stu); break;/* Search for book information */
case 4: change(stu); break;/* Modify book information */
case 5: deletel(stu); break;/* Delete book information */
case 6: sort(stu); break;/* Book price information ranking */
case 0: break;
}
}while(choice!=0);
save_file(stu,sum);
}
int main()
{
int i,sum;
pquantitydis();
check();
menu();
}For more information, please refer to the topic “management system development”.