I do not know how let this C program run correctly

sami sam

14y1.4kVisual Basic .NET

#include

char s[80];

int i, j,n;

int main() {

printf("Type in a word: ");

scanf("%s",s);

printf("Type in a number: ");

scanf("%d",&n);

i = 0;

j = strlen -1;

while (i < j) {

printf("%c",s[i]);

i = i + n;

}

5 Replies

Know the answer? Post it — somebody with the same question will find it here.

Glenn Patton14y ago
Ahh, yes so it is, my apologies. My memory of these types of exercises are foggy, I spent most of the time thinking "why would you want to do that?" Glenn
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Vulpes14y ago
'n' is set equal to the number entered at the console via the scanf() function.

The idea seems to be to print the first character of the input string, the (1 + n)th character, the (1 + 2n)th character and so on until the penultimate character of the string is reached.

So, if you entered 'glenn' and 2, the program would print 'ge' to the console. That's because 'j' would be 4 and so 'i' would go from 0 to 2 before the while loop ended.

Possibly, the loop should continue until the final character of the string is reached - in which case j should be set to strlen(s). We just don't know as we haven't seen the original question.
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Glenn Patton14y ago
Hi Vulpes, You haven't set n to equal a value so there could be a loop with randomness in it. I think he is after i++, rather than i=i+n........
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Vulpes14y ago
Yes, Glenn's right.

You need to include string.h to use the strlen function and the latter needs to have an argument passed to it. The following compiles and runs fine:

#include
#include

char s[80];
int i, j,n;

int main() {
printf("Type in a word: ");
scanf("%s",s);
printf("Type in a number: ");
scanf("%d",&n);
i = 0;
j = strlen(s) -1;
while (i < j) {
printf("%c",s[i]);
i = i + n;
}
}
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Glenn Patton14y ago
Umm, Homework? without entering it to a debugger (your job!) from looking over it think about the while loop i < j, i = i+n, n = ? random stuff most likely, try looking at for loops for a way to increase i. Also you might want to have a look at new line carriage returns characters.

Glenn
Got board at lunch had another look also you are trying to use string length with out the header included (string.h) and the string length is wrong have a look at using strlen correctly!
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