c - 无效的初始值设定项 : strcat(s, str)；在C程序中

Question

我正在 hackerrank 中编写程序，并尝试使用 strcat() 函数连接两个字符串，但它对我不起作用。

我是学生，正在学习 C 语言，你能帮我找到连接两个字符串的方法吗？

这是我的代码:

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

int main() {
    int i = 4;
    double d = 4.0;
    char s[] = "HackerRank ";

    // Declare second integer, double, and String variables.
    int j;
    double e;
    char str[] = "";

    // Read and save an integer, double, and String to your variables.
    scanf("Enter integer : %d",&j);
    scanf("Enter double : %lf",&e);
    scanf("Enter string : %s",str);

    // Print the sum of both integer variables on a new line.
    int sum = i + j;
    printf("\n %d",sum);

    // Print the sum of the double variables on a new line.
    double doubleSum = d + e;
    printf("\n %lf",doubleSum);

    // Concatenate and print the String variables on a new line
    char finalString[] = strcat(s,str);
    printf("%s",finalString);

    // The 's' variable above should be printed first.
    return 0;
}

错误:

solution.c: In function ‘main’:
solution.c:30:26: error: invalid initializer
     char finalString[] = strcat(s,str);
                          ^~~~~~

Compiler Error

Answer 1

检查下面的代码:

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

int main() {
    int i = 4;
    double d = 4.0;
    char s[] = "HackerRank ";
    char *finalString = NULL;
    int j;
    double e;
    char str[100];
    scanf("%d",&j);
    scanf("%lf",&e);
    scanf("%s", &str);
    int sum = i + j;
    printf("\n %d",sum);
    double doubleSum = d + e;
    printf("\n %lf",doubleSum);
    finalString = realloc(finalString, strlen(s) + strlen(str) + sizeof(char));
    strcat(finalString,s);
    printf("\n %s",finalString);    
    strcat(finalString,str);
    printf("\n %s \n",finalString);
   return 0;
}