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String comparison: Difference between revisions
c entry
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''cm'' is used for comparision which returns 1,0,-1 like C's strcmp. ''=='' is Equal and ''!='' is NotEqual.
=={{header|c}}==
'''Solution'''
c provides the strcmp and strcasecmp functions for lexical comparison of ASCIIz strings, with declarations found in string.h . strcmp causes a good deal of confusion because it returns 0 when the strings are equal. Hence the likely looking common mistake
if (strcmp(a,b)) action_on_equality();
Wrapping strcmp with macros or functions makes good sense. c has other functions to compare binary data, version strings, wide character strings, and strings in current locale. These behave similarly.
<lang c>
/*
compilation and test in bash
$ a=./c && make $a && $a ball bell ball ball YUP YEP ball BELL ball BALL YUP yep
cc -Wall -c -o c.o c.c
eq , ne , gt , lt , ge , le
ball 0 1 0 1 0 1 bell
ball 0 1 0 1 0 1 bell ignoring case
ball 1 0 0 0 1 1 ball
ball 1 0 0 0 1 1 ball ignoring case
YUP 0 1 1 0 1 0 YEP
YUP 0 1 1 0 1 0 YEP ignoring case
ball 0 1 1 0 1 0 BELL
ball 0 1 0 1 0 1 BELL ignoring case
ball 0 1 1 0 1 0 BALL
ball 1 0 0 0 1 1 BALL ignoring case
YUP 0 1 0 1 0 1 yep
YUP 0 1 1 0 1 0 yep ignoring case
*/
#include<string.h>
#define STREQ(A,B) (0==strcmp((A),(B)))
#define STRNE(A,B) (!STREQ(A,B))
#define STRLT(A,B) (strcmp((A),(B))<0)
#define STRLE(A,B) (strcmp((A),(B))<=0)
#define STRGT(A,B) STRLT(B,A)
#define STRGE(A,B) STRLE(B,A)
#define STRCEQ(A,B) (0==strcasecmp((A),(B)))
#define STRCNE(A,B) (!STRCEQ(A,B))
#define STRCLT(A,B) (strcasecmp((A),(B))<0)
#define STRCLE(A,B) (strcasecmp((A),(B))<=0)
#define STRCGT(A,B) STRCLT(B,A)
#define STRCGE(A,B) STRCLE(B,A)
#include<stdio.h>
void compare(char*a, char*b) {
printf("%s%2d%2d%2d%2d%2d%2d %s\n",
a,
STREQ(a,b), STRNE(a,b), STRGT(a,b), STRLT(a,b), STRGE(a,b), STRLE(a,b),
b
);
}
void comparecase(char*a, char*b) {
printf("%s%2d%2d%2d%2d%2d%2d %s ignoring case\n",
a,
STRCEQ(a,b), STRCNE(a,b), STRCGT(a,b), STRCLT(a,b), STRCGE(a,b), STRCLE(a,b),
b
);
}
int main(int ac, char*av[]) {
char*a,*b;
puts("\teq , ne , gt , lt , ge , le");
while (0 < (ac -= 2)) {
a = *++av, b = *++av;
compare(a, b);
comparecase(a, b);
}
return 0;
}
</lang>
=={{header|D}}==
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