[英]What's wrong with my code function to make strcat function in C?
#include <stdio.h>
#include <stdlib.h>
char wordsum(char FW[256],char SW[256]){
int i;
int j=strlen(FW);
for (i=0;i<=strlen(SW);i++)
FW[i+j+1]=SW[i];
printf("%c",FW);
return FW;
}
int main()
{
char F[256];
char S[256];
printf("Enter the first word\n");
gets(F);
printf("Enter the Second word\n");
gets(S);
wordsum(F,S);
return 0;
}
I don't know what is wrong with my code to make strcat
function. 我不知道我的使
strcat
函数起作用的代码有什么问题。 I hope to find the answer. 我希望找到答案。
I assume that the code is written to learn more about the C language. 我认为代码编写,详细了解C语言。 If so, may I present an alternative implementation which does not use strlen().
如果是这样,我可以提出一个不使用strlen()的替代实现。 The intention is to present some of the really nice features in the language.
其目的是提出一些非常好的功能的语言。 It may be a bit complicated to wrap ones head around the first time, but IIRC the code can be found in K&R's book The C Programming Language.
第一次绕头看可能有点复杂,但是IIRC代码可以在K&R的书The C Programming Language中找到。
Here we go: 开始了:
char* mystrcat(char *dest, const char *src)
{
char *ret = dest;
while (*dest)
dest++;
while ((*dest++ = *src++))
;
return ret;
}
The first while-loop finds the end of the destination string. 第一个while循环查找目标字符串的结尾。 The second while-loop appends the source string to the destination string.
第二个while循环将源字符串附加到目标字符串。 Finally, we return a pointer to the original dest buffer.
最后,我们的指针回到原来的DEST缓冲。
The function could've been even nicer if it didn't return a pointer. 如果不返回指针,该函数本来可以更好。
void mystrcat(char *dest, const char *src)
{
while (*dest)
dest++;
while ((*dest++ = *src++))
;
}
HTH 高温超导
There are a few problems in your function, I've changed and commented them below: 您的函数中存在一些问题,下面我对它们进行了更改和评论:
char *wordsum(char FW[256],char SW[256]){ // correct function type
int i;
int j=strlen(FW);
for (i = 0; i <= strlen(SW); i++)
FW[i+j] = SW[i]; //change 'i + j + 1' to 'i + j'
printf("%s",FW); //change format specifier as you are printing string not character
return FW;
}
Then dot forget to capture the returned pointer using a char*
variable in the calling function (here main()
) 然后点忘了使用调用函数中的
char*
变量来捕获返回的指针(此处为main()
)
char *result;
result = wordsum(F,S);
printf("\n%s\n", result);
Working example: https://ideone.com/ERlFPE 工作示例: https : //ideone.com/ERlFPE
There are several mistakes in your code. 您的代码中有几个错误。 They are:
他们是:
1) A function can't return an array in C and you don't need to do so. 1)函数无法在C中返回数组,因此您不需要这样做。 Change the return type from
char
to void
of wordsum
and erase the line return FW;
将返回类型从
char
更改为wordsum
void
,并删除行return FW;
2) You want to print a string, right? 2)您想打印一个字符串,对吗? Format specifier for string is
%s
. 字符串的格式说明符为
%s
。 So write printf("%s",FW);
因此写出
printf("%s",FW);
instead of printf("%c",FW);
而不是
printf("%c",FW);
. 。
3) Do this: FW[i+j]=SW[i];
3)这样做:
FW[i+j]=SW[i];
. 。 Why did you add an extra 1 to
i+j
? 您为什么要在
i+j
加1? Just think logically. 只是逻辑地思考。
4) Add header file for strlen()
, it's <string.h>
. 4)为
strlen()
)添加头文件,它是<string.h>
。
5) Erase those asterisk marks before and after FW[i+j]=SW[i];
5)擦除
FW[i+j]=SW[i];
之前和之后的那些星号FW[i+j]=SW[i];
. 。
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