程序在接受C中的输入中的第二个字符串之前运行

Question

I am trying to run the following code but the program accepts only one string and displays the output immediately without waiting for the second string to be entered. The program is for 2 string concatenation. Here is the code :-

#include <stdio.h>

main()
{
    int i, j, len=0;
    char name[100], abc[100];

    printf("\nPlease Enter String 1 =\t");
    scanf("%[^\n]c",&name);
    printf("\nPlease Enter String 2 =\t");
    scanf("%[^\n]c",&abc);

    for(i=0; name[i]!='\0'; i++)
        len++;
    for(j=0; abc[j]!='\0'; j++)
    {
        len++;
        name[len]=abc[j];
    }

    printf("\nThe Concatenated String Is =\t");
    puts(name);
}

Answer 1

Use the following scanf instead:

scanf("%[^\n]",name);
.....
scanf(" %[^\n]",abc);

Please refer to this scanf() manual page for more detail of how to use scanf() .

Answer 2

Use fgets instead of scanf, also you were incrementing len at the wrong place:

#include <stdio.h>
#include <string.h>
int main() {
    int len = 0;
    char name[100], abc[100];
    printf("\nPlease Enter String 1 =\t");
    fgets(name, 100, stdin);
    len = strlen(name) - 1;
    name[len] = 0;
    printf("\nPlease Enter String 2 =\t");
    fgets(abc, 100, stdin);
    abc[strlen(abc) - 1] = 0;
    strcpy(name+len, abc);
    printf("\nThe Concatenated String Is =\t");
    puts(name);
    return 0;
}

Answer 3

You have to throw away the newline character ('\\n').

Try:

while(getchar() != '\n')
    continue;

after each scanf

Answer 4

I would like to suggest you not to use scanf . Better to use fgets instead.
By the way the reason that your program accepts only one string and displays the output immediately without waiting for the second string to be entered is the \\n character left behind by the first scanf after pressing the Enter key. To eat up this newline character you may use gatchar() after first scanf .

printf("\nPlease Enter String 1 =\t");
scanf("%[^\n]c",name);
getchar();
printf("\nPlease Enter String 2 =\t");
scanf("%[^\n]c",abc);  

Other two mistakes are:
1. Wrong increment of len

for(i=0; name[i]!='\0'; i++)
    len++;
for(j=0; abc[j]!='\0'; j++)
{
    name[len++]=abc[j];  
}   

2. Reason for weird output is the string is not NUL terminated. Add this line after second for loop.

name[len] = '\0'; // add this to null terminate your string.  

Here is your working Code

Answer 5

should be

scanf("%[^\n]%*c", name);
printf("\nPlease Enter String 2 =\t");
scanf("%[^\n]%*c", abc);
for(i=0;name[i]!='\0';i++)
    len++;
for(j=0;abc[j]!='\0';j++){
    name[len]=abc[j];
    len++;
}
name[len]='\0';