C & cmd

命令列引數

C語言部份:
#include <stdio.h>
#include <stdlib.h>

/* run this program using the console pauser or add your own getch, system("pause") or input loop */

int main(int argc, char *argv[]) {

printf("testing now\n");
if(argc!=3){
printf("successful part1\n");
}


printf("%s",argv[0]);





return 0;
}
CMD部分:

PS:利用cmd開啟exe檔 並在其後輸入argc的值，可引入函數



重導

https://www.youtube.com/watch?v=xQXAnI9-Z2I&list=PLFI-nbR0eXR5x192m3XVGJzfJxbEcRo2Z&index=9

C&sql

使用C寫入資料庫

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


int main(int argc, char *argv[]) {
int account;
char name[30];
double balance;
FILE *cfptr;
if((cfptr=fopen("clients2.dat","w"))==NULL){
printf("file could not be opened\n");

}
else{
printf("enter the account ,name,and balance.\n");
printf("enter EOF to end inpute.\n");
printf("?");
scanf("%d%s%.2f",&account,name,&balance);
while(!feof(stdin)){
fprintf(cfptr,"%d %s %.2f\n",account,name,balance);
printf("?");
scanf("%d%s%lf",&account,name,&balance);

}
fclose(cfptr);
}
return 0;
}


PS1:寫入同檔案夾中的資料庫，名字取決於此處clients2:if((cfptr=fopen("clients2.dat","w"))==NULL){
PS2:fopen(檔案名稱, 模式) 以指定模式開啟檔案 其中"W"代表寫入
*************************
使用C讀入資料庫
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
int account;
char name[30];
double balance;
FILE *cfptr;
if((cfptr=fopen("clients.dat","r"))==NULL){
printf("could not open\n");

}
else {
printf("%-10s%-13s%s\n","account","name","balance");
fscanf(cfptr,"%d%s%lf",&account,name,&balance);
while(!feof(cfptr)){
printf("%-10d%-13s%7.2f\n",account,name,balance);
fscanf(cfptr,"%d%s%lf",&account,name,&balance);
}
fclose(cfptr);
}
return 0;
}