Question

这是一个简单的程序：通过main函数传递用户输入，以计算一系列整数的范围。但是，该程序默认使用功能。换句话说，它似乎不接受来自命令行的输入。

程序执行，但在某个地方它会达到将使用消息打印到终端的条件。

以下是该计划：

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

int range(int a[], int *n, int *rng){
  //Declarations
  int i; //Dummy variable
  int min;
  int max;

  //Validate input
  if(!a || !n || !rng || *n <= 0) return -1;

  //Main execution
  min = a[0];
  max = a[0];

  for(i=0; i<*n; i++){
         if(a[i]<min)
                     min = a[i];
         if(a[i]>max)
                     max = a[i];  
  }
  *rng = max-min;
  return 0;
 }

void printUsage() {
   printf("\nUsage:[-s <series of at least two integers>] [-h help].");
}

int main(int argc, char **argv){
//Declarations
int setInt[100];
int i; //Dummy index
int n; //Temp variable
int err;
int rng;


//Run some tests to determine validity of input
for(i=0; i<argc; i++){

         //Is there at least some user input?
         if(argc == 1){ 
                 printUsage();
                 return -1;
         }
         //Determine if the user requested usage
         if(strcmp("-h", argv[i]) == 0){
                              printUsage();
                              return -1; //TRY REMOVING LATER TO SEE IF PROGRAM CAN KEPP RUNNING
         }
         //Determine if the user entered some data
         else if(strcmp("-s", argv[i]) == 0){
                              //There must be at least TWO arguments after this call
                              if((i+1) == argc || (i+2) == argc){
                                     printUsage();
                                     return -1;
                              }

                              //Start another loop to fill an array of values the user entered
                              //Reuse i, but start at three to grap the first supposed integer
                              for(i=3; i < argc; i++){
                                       err = sscanf(argv[i], "%d", &n);
                                       if(err == 0) {//The input wasn't an integer
                                              printUsage();
                                              return -1;
                                       }
                                       else {
                                            assert(err == 1);
                                            setInt[i-3] = n; //Store the variable in an array
                                       }                 
                              }


              }

         else{//unknown input
                        printUsage();
                        return -1;
         }
//For bracket
}

//Call the function

printf("The range of values entered is %d.", rng);
range(setInt, &argc, &rng);
getchar();
getchar();
return 0;
//Main bracket
}

Answer 1

问题是你在寻找-s之前不要增加i 改变行

     else if(strcmp("-s", argv[i]) == 0){ //i is still zero, so argv[i] is the command entered

到

     else if(strcmp("-s", argv[++i]) == 0){

（在i之前添加++）并且它不会打印用法。

这个C程序中的逻辑错误在哪里？

1 个答案: