Question

我是C的新手，我无法弄清楚如何在控制台中传递此错误时摆脱此错误。我试着看其他问题，但实际上我不知道该寻找什么。我试着看看argv的通行证，但没有找到任何突出的东西。

./calculate factorial 4

Segmentation fault (core dumped)

程序：

#include "calculate.h"

int main(int argc, char * argv[])
{
    if(strcmp(argv[1], "factorial") == 0){
        int result = factorial(argc, argv);
        printf("%d\n", result);
    }
    else if(strcmp(argv[1], "combination") == 0){
        int result = combination(argc, argv);
        printf("%d\n", result);
    }
    else if(strcmp(argv[1], "permutation") == 0){
        int result = permutation(argc, argv);
        printf("%d\n", result);
    }
    else if(strcmp(argv[1], "pythagorean") == 0){
        int result = pythagorean(argc, argv);
        printf("%d\n", result);
    }
    else{
    printf("You did not use a valid input!\n");
    }

    printf("Assignment1-4");
    return 0;
}

int factorial(int argc, char * argv[]){
    int i = atoi(argv[3]);
    if ( i == 0 ){
        return 1;
    }
    return(i * factorial((i - 1),argv));
}

int combination(int argc, char * argv[]){
    int n = atoi(argv[3]);
    int i = atoi(argv[4]);
    return(factorial(n,argv) / (factorial(i,argv) * factorial((n- i), argv)));
}

int permutation(int argc, char * argv[]){
    int n = atoi(argv[3]);
    int i = atoi(argv[4]);
    return(factorial(n,argv) / factorial((n-i), argv));
}

int pythagorean(int argc, char * argv[]){
    int c = 0;
    int a = atoi(argv[3]);
    int b = atoi(argv[4]);
    c = (a*a) + (b*b);
    c = sqrt(c);
    return c;
}

我只是找不到问题，谢谢。

Answer 1

在函数factorial（）中，将argv [3]赋值给i。但是，当您使用./calculate factorial 4运行程序时，您没有argv [3]条目。这意味着argc只有3（argv数组的长度是3）。您正在访问其范围之外的argv []数组。使用i = atoi(argv[2])获取预期值。

同样在递归调用中，i总是用argv []值初始化。所以它永远不会达到0并导致无限循环。

如下所示写factorial（）并从main（）调用factorial(atoi(argv[2]))

int factorial(int i){                                                      
if ( i == 0 ){                                                              
    return 1;                                                               
}                                                                           
return(i * factorial((i - 1));                                        
}

Answer 2

你为参数3和4屈服，但你永远不会提供这些参数。所以有例外。在这里你应该如何实施该程序

这里是

的命令

./calculate factorial 4 
./calculate combination 4 3
./calculate permutation 6 3
./calculate pythagorean 3 4

这是源

#include <stdio.h>
#include <math.h>


int main(int argc, char* argv[])
{
   if(strcmp(argv[1], "factorial") == 0){
        int result = factorial(atoi(argv[2]));
        printf("%d\n", result);
    }
    else if(strcmp(argv[1], "combination") == 0){
        int result = combination(atoi(argv[2]), atoi(argv[3]));
        printf("%d\n", result);
    }
    else if(strcmp(argv[1], "permutation") == 0){
        int result = permutation(atoi(argv[2]), atoi(argv[3]));
        printf("%d\n", result);
    }
    else if(strcmp(argv[1], "pythagorean") == 0){
        int result = pythagorean(atoi(argv[2]), atoi(argv[3]));
        printf("%d\n", result);
    }
    else{
    printf("You did not use a valid input!\n");
    }
    printf("Assignment1-4");
    return 0;
}
int factorial(int i){
    if ( i == 0 ){
        return 1;
    }
    return(i * factorial(i-1));
}
int combination(int n, int i){
    return(factorial(n) / (factorial(i) * factorial((n- i))));
}
int permutation(int n, int i){
    return(factorial(n) / factorial(n-i));
}
int pythagorean(int a, int b){
    int c = 0;
    c = (a*a) + (b*b);
    c = sqrt(c);
    return c;
}

程序中的分段错误（核心转储）错误

2 个答案: